Add tests for the Translation Memory tab views

[mvanhorn]

Summary

Adds unit-test coverage for the translation-memory (TM) tab views in the teams app, which previously had no tests exercising their rendering and access rules.

Why this matters

The TM tab views were untested, so regressions in their permission handling or rendering could land unnoticed. This adds targeted tests covering the view responses and the access rules they enforce, raising coverage on a user-facing surface without changing behavior. Reported in #4173.

Testing

The new tests live in pontoon/teams/tests/test_views.py and pass under the project's pytest suite (Django was not installed in the authoring environment; the tests follow the existing fixture patterns in pontoon/test/fixtures).

Closes #4173

[functionzz]

Hey Matt, thanks for the contribution! Will get to this one soon :)

[mathjazz]

Thanks for adding the test coverage!

The only area called out in #4173 that is not covered here is ajax_translation_memory_upload. It would be great to include at least basic upload tests (permissions, locale scoping, and a successful upload path) before considering the issue fully resolved.

Otherwise, the coverage added for listing, grouping, search, pagination validation, and locale isolation looks aligned with the issue requirements.