chore(debugger): reduce debugger test flakiness [backport #4528 to 1.6] (#4864)

## Description
Taken from:
P403n1x87@ed5b716
This is required to reduce flakiness in one of the debugger tests:
test_debugger_probe_new_delete[probe0-<lambda>] Example failure:
https://app.circleci.com/pipelines/github/DataDog/dd-trace-py/23627/workflows/79199172-b4ef-43b3-a69e-371660cb1b68/jobs/1604074

## Checklist
- [x] Add additional sections for `feat` and `fix` pull requests.
- [x] [Library
documentation](https://github.com/DataDog/dd-trace-py/tree/1.x/docs)
and/or [Datadog's documentation
site](https://github.com/DataDog/documentation/) is updated. Link to doc
PR in description.

## Reviewer Checklist
- [x] Title is accurate.
- [x] Description motivates each change.
- [x] No unnecessary changes were introduced in this PR.
- [x] Avoid breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [ ] Tests provided or description of manual testing performed is
included in the code or PR.
- [x] Release note has been added for fixes and features, or else
`changelog/no-changelog` label added.
- [x] All relevant GitHub issues are correctly linked.
- [ ] Backports are identified and tagged with Mergifyio.

## Description
<!-- Briefly describe the change and why it was required. -->

<!-- If this is a breaking change, explain why it is necessary. Breaking
changes must append `!` after the type/scope. See
https://ddtrace.readthedocs.io/en/stable/contributing.html for more
details. -->

## Checklist
- [ ] Followed the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines)
when writing a release note.
- [ ] Add additional sections for `feat` and `fix` pull requests.
- [ ] [Library
documentation](https://github.com/DataDog/dd-trace-py/tree/1.x/docs)
and/or [Datadog's documentation
site](https://github.com/DataDog/documentation/) is updated. Link to doc
PR in description.

<!-- Copy and paste the relevant snippet based on the type of pull
request -->

<!-- START feat -->

## Motivation
<!-- Expand on why the change is required, include relevant context for
reviewers -->

## Design 
<!-- Include benefits from the change as well as possible drawbacks and
trade-offs -->

## Testing strategy
<!-- Describe the automated tests and/or the steps for manual testing.

<!-- END feat -->

<!-- START fix -->

## Relevant issue(s)
<!-- Link the pull request to any issues related to the fix. Use
keywords for links to automate closing the issues once the pull request
is merged. -->

## Testing strategy
<!-- Describe any added regression tests and/or the manual testing
performed. -->

<!-- END fix -->

## Reviewer Checklist
- [ ] Title is accurate.
- [ ] Description motivates each change.
- [ ] No unnecessary changes were introduced in this PR.
- [ ] Avoid breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [ ] Tests provided or description of manual testing performed is
included in the code or PR.
- [ ] Release note has been added and follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines),
or else `changelog/no-changelog` label added.
- [ ] All relevant GitHub issues are correctly linked.
- [ ] Backports are identified and tagged with Mergifyio.

Co-authored-by: Zachary Groves <[email protected]>

Author: Yun-Kim

ddtrace/internal/module.py

@@ -211,7 +211,7 @@ class ModuleWatchdog(dict):
     def __init__(self):
         # type: () -> None
         self._hook_map = defaultdict(list)  # type: DefaultDict[str, List[ModuleHookType]]
-        self._origin_map = {origin(module): module for module in sys.modules.values()}
+        self._om = None  # type: Optional[Dict[str, ModuleType]]
         self._modules = sys.modules  # type: Union[dict, ModuleWatchdog]
         self._finding = set()  # type: Set[str]
 
@@ -223,6 +223,21 @@ def __setitem__(self, name, module):
         # type: (str, ModuleType) -> None
         self._modules.__setitem__(name, module)
 
+    @property
+    def _origin_map(self):
+        # type: () -> Dict[str, ModuleType]
+        if self._om is None:
+            try:
+                self._om = {origin(module): module for module in sys.modules.values()}
+            except RuntimeError:
+                # The state of sys.modules might have been mutated by another
+                # thread. We try to build the full mapping at the next occasion.
+                # For now we take the more expensive route of building a list of
+                # the current values, which might be incomplete.
+                return {origin(module): module for module in list(sys.modules.values())}
+
+        return self._om
+
     def _add_to_meta_path(self):
         # type: () -> None
         sys.meta_path.insert(0, self)  # type: ignore[arg-type]