Improve CallableType join in simple cases

[hauntsaninja]

Fixes #17479 , although as you can see in the test case the logic still remains far from perfect

[hauntsaninja]

ddtrace:
fixes false positive in utils_redis.py
schema is because we have a nested dict, so inferring narrower types on the inner dicts means the outer dict becomes dict[str, object] instead of dict[str, dict[str, builtins.function]]
span_attribute_schema seems regrettable, let me see what i can do

prefect:
fixes false positive in profile.py
it's unclear to me how provisioners was working earlier, was it inferring a union? will look further

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

prefect (https://github.com/PrefectHQ/prefect)
- src/prefect/cli/profile.py:178: error: Cannot call function of unknown type  [operator]
+ src/prefect/infrastructure/provisioners/__init__.py:57: error: Incompatible return value type (got "object", expected "type[Provisioner]")  [return-value]

pydantic (https://github.com/pydantic/pydantic)
+ pydantic/_internal/_std_types_schema.py:81: error: Argument 2 to <set> has incompatible type "type[Path]"; expected "type[PathLike[AnyStr_co]]"  [arg-type]
+ pydantic/_internal/_std_types_schema.py:82: error: Argument 3 to <set> has incompatible type "type[PurePath]"; expected "type[PathLike[AnyStr_co]]"  [arg-type]
+ pydantic/_internal/_std_types_schema.py:83: error: Argument 4 to <set> has incompatible type "type[PosixPath]"; expected "type[PathLike[AnyStr_co]]"  [arg-type]
+ pydantic/_internal/_std_types_schema.py:84: error: Argument 5 to <set> has incompatible type "type[PurePosixPath]"; expected "type[PathLike[AnyStr_co]]"  [arg-type]
+ pydantic/_internal/_std_types_schema.py:85: error: Argument 6 to <set> has incompatible type "type[PureWindowsPath]"; expected "type[PathLike[AnyStr_co]]"  [arg-type]

pandas (https://github.com/pandas-dev/pandas)
+ pandas/tests/io/formats/test_console.py:57: error: List item 1 has incompatible type "type[Error]"; expected "type[AttributeError]"  [list-item]

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/transforms/__init__.py:239:5: error: Dict entry 4 has incompatible type "str": "type[image]"; expected "str": "type[TextElement]"  [dict-item]

dd-trace-py (https://github.com/DataDog/dd-trace-py)
+ ddtrace/internal/schema/__init__.py:43: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:44: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:45: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:46: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:47: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:48: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:49: error: Value of type "object" is not indexable  [index]
+ ddtrace/internal/schema/__init__.py:50: error: Value of type "object" is not indexable  [index]
+ ddtrace/_trace/utils_redis.py:35: error: Unused "type: ignore" comment  [unused-ignore]

steam.py (https://github.com/Gobot1234/steam.py)
+ steam/ext/commands/commands.py:851: error: Overloaded function implementation does not accept all possible arguments of signature 1  [misc]

pandera (https://github.com/pandera-dev/pandera)
+ tests/core/test_decorators.py:502: error: List item 0 has incompatible type "tuple[int, type[TypeError], None]"; expected "tuple[object, type[AttributeError], str | None]"  [list-item]
+ tests/core/test_decorators.py:503: error: List item 1 has incompatible type "tuple[float, type[TypeError], None]"; expected "tuple[object, type[AttributeError], str | None]"  [list-item]
+ tests/core/test_decorators.py:504: error: List item 2 has incompatible type "tuple[str, type[TypeError], None]"; expected "tuple[object, type[AttributeError], str | None]"  [list-item]
+ tests/core/test_decorators.py:505: error: List item 3 has incompatible type "tuple[list[str], type[ValueError], str]"; expected "tuple[object, type[AttributeError], str | None]"  [list-item]

ibis (https://github.com/ibis-project/ibis)
+ ibis/tests/expr/test_table.py:577: error: List item 0 has incompatible type "tuple[str, type[IbisTypeError]]"; expected "tuple[Any, type[AttributeError]]"  [list-item]
+ ibis/tests/expr/test_table.py:578: error: List item 1 has incompatible type "tuple[tuple[str, bool], type[IbisTypeError]]"; expected "tuple[Any, type[AttributeError]]"  [list-item]
+ ibis/tests/expr/test_table.py:579: error: List item 2 has incompatible type "tuple[Value, type[IbisTypeError]]"; expected "tuple[Any, type[AttributeError]]"  [list-item]

spack (https://github.com/spack/spack)
+ lib/spack/spack/test/repo.py:226: error: List item 1 has incompatible type "type[RepoPath]"; expected "type[Repo]"  [list-item]
+ lib/spack/spack/test/repo.py:266: error: List item 1 has incompatible type "type[RepoPath]"; expected "type[Repo]"  [list-item]
+ lib/spack/spack/test/repo.py:272: error: List item 1 has incompatible type "type[RepoPath]"; expected "type[Repo]"  [list-item]
+ lib/spack/spack/test/repo.py:282: error: List item 1 has incompatible type "type[RepoPath]"; expected "type[Repo]"  [list-item]

poetry (https://github.com/python-poetry/poetry)
+ tests/utils/test_isolated_build.py:62: error: List item 0 has incompatible type "tuple[set[str], type[IncompatibleConstraintsError]]"; expected "tuple[set[str], type[SolverProblemError]]"  [list-item]

scikit-learn (https://github.com/scikit-learn/scikit-learn)
+ sklearn/feature_extraction/tests/test_text.py:1406: error: List item 0 has incompatible type "tuple[str, type[FileNotFoundError], str]"; expected "tuple[str, type[AttributeError], str]"  [list-item]
+ sklearn/model_selection/tests/test_classification_threshold.py:204: error: List item 0 has incompatible type "tuple[dict[str, object], type[ValueError], str]"; expected "tuple[object, type[NotFittedError], str]"  [list-item]
+ sklearn/model_selection/tests/test_classification_threshold.py:209: error: List item 1 has incompatible type "tuple[dict[str, int], type[ValueError], str]"; expected "tuple[object, type[NotFittedError], str]"  [list-item]
+ sklearn/feature_selection/tests/test_rfe.py:485: error: List item 0 has incompatible type "tuple[str, type[ValueError]]"; expected "tuple[object, type[AttributeError]]"  [list-item]