Remove logic for legacy bundled stubs

[hauntsaninja]

For mypy v2

[github-actions]

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

prefect (https://github.com/PrefectHQ/prefect)
- src/prefect/server/api/collections.py:6: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/settings/sources.py:9: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/_internal/compatibility/deprecated.py:66: error: Library stubs not installed for "dateparser"  [import-untyped]
- src/prefect/_internal/compatibility/deprecated.py:66: note: Hint: "python3 -m pip install types-dateparser"
- src/prefect/_internal/compatibility/deprecated.py:66: note: (or run "mypy --install-types" to install all missing stub packages)
- src/prefect/_internal/compatibility/deprecated.py:66: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
- src/prefect/server/utilities/messaging/memory.py:17: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/logging/clients.py:16: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/server/events/ordering/memory.py:11: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/events/clients.py:20: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/concurrency/services.py:9: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/concurrency/services.py:9: note: Hint: "python3 -m pip install types-cachetools"
- src/prefect/task_runs.py:10: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/_waiters.py:13: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/server/events/actions.py:36: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/results.py:23: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/server/models/events.py:5: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/server/database/query_components.py:18: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/runner/runner.py:72: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/server/events/ordering/db.py:13: error: Library stubs not installed for "cachetools"  [import-untyped]
- src/prefect/cli/deployment.py:922: error: Library stubs not installed for "dateparser"  [import-untyped]

trio (https://github.com/python-trio/trio)
- src/trio/_tools/sync_requirements.py:12: error: Library stubs not installed for "yaml"  [import-untyped]
- src/trio/_tests/tools/test_sync_requirements.py:10: error: Library stubs not installed for "yaml"  [import-untyped]
- src/trio/_tests/tools/test_sync_requirements.py:10: note: Hint: "python3 -m pip install types-PyYAML"
- src/trio/_tests/tools/test_sync_requirements.py:10: note: (or run "mypy --install-types" to install all missing stub packages)
- src/trio/_tests/tools/test_sync_requirements.py:10: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

pandas-stubs (https://github.com/pandas-dev/pandas-stubs)
- pandas-stubs/tseries/holiday.pyi:11: error: Library stubs not installed for "dateutil.relativedelta"  [import-untyped]
- pandas-stubs/_libs/tslibs/offsets.pyi:15: error: Library stubs not installed for "dateutil.relativedelta"  [import-untyped]
- pandas-stubs/_libs/tslibs/offsets.pyi:15: note: Hint: "python3 -m pip install types-python-dateutil"
- pandas-stubs/_libs/tslibs/offsets.pyi:15: note: (or run "mypy --install-types" to install all missing stub packages)
- pandas-stubs/_libs/tslibs/offsets.pyi:15: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
- tests/test_timefuncs.py:6: error: Library stubs not installed for "dateutil.relativedelta"  [import-untyped]
- tests/scalars/test_scalars.py:11: error: Library stubs not installed for "dateutil.tz"  [import-untyped]
- tests/scalars/test_scalars.py:11: error: Library stubs not installed for "dateutil"  [import-untyped]

openlibrary (https://github.com/internetarchive/openlibrary)
- openlibrary/solr/update.py:8: error: Library stubs not installed for "aiofiles"  [import-untyped]
- openlibrary/solr/update.py:8: note: Hint: "python3 -m pip install types-aiofiles"
- openlibrary/solr/update.py:8: note: (or run "mypy --install-types" to install all missing stub packages)
- openlibrary/solr/update.py:8: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports