ci(django): disable failing test [backport #6259 to 1.15] (#6337)

Backport of #6259 to 1.15

The test started failing after the image was fixed. It is unclear why
the test is failing, but at least it doesn't seem related to `ddtrace`.

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Co-authored-by: David Sanchez <[email protected]>
Co-authored-by: Munir Abdinur <[email protected]>

Author: 3 people

.github/workflows/test_frameworks.yml

@@ -142,6 +142,7 @@ jobs:
           sed -i'' 's/test_multivalue_dict_key_error/multivalue_dict_key_error/' tests/view_tests/tests/test_debug.py  # Sensitive data leak
           sed -i'' 's/test_db_table/db_table/' tests/schema/tests.py
           sed -i'' 's/test_django_admin_py_equivalent_main/django_admin_py_equivalent_main/' tests/admin_scripts/test_django_admin_py.py
+          sed -i'' 's/test_custom_fields/custom_fields/' tests/inspectdb/tests.py
 
       - name: Run tests
         # django.tests.requests module interferes with requests library patching in the tracer -> disable requests patch