ci: add stack v2 profiling to Django profiling (#11291)

We enable the stack v2 profiler in the Django overhead profiling for
collecting profiles using the Datadog profiler, while also profiling any
additional overhead introduced by the profiler itself.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- 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)

.github/workflows/django-overhead-profile.yml

@@ -16,6 +16,9 @@ jobs:
     env:
       PREFIX: ${{ github.workspace }}/prefix
       DD_CODE_ORIGIN_FOR_SPANS_ENABLED: "1"
+      DD_PROFILING_ENABLED: "1"
+      DD_PROFILING_STACK_V2_ENABLED: "1"
+      DD_PROFILING_OUTPUT_PPROF: ${{ github.workspace }}/prefix/artifacts/ddtrace_profile.pprof
     defaults:
       run:
         working-directory: ddtrace