[3.15] pytest_bdd / pytest_benchmark / unittest / freezegun / selenium — enable on Python 3.15

[vlad-scherbich]

Tracked under parent: #17809

Tier: B
Section: CI Visibility — @DataDog/ci-app-libraries

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Original row from the parent tracker:

• pytest_bdd, pytest_benchmark, unittest, freezegun, selenium — re-validate at 3.15 once pytest is unblocked

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To close this row, open a PR using the python_315_bump template (added in #17791; open via ?template=python_315_bump.md) and include Closes #<this-issue-number> in the description. That auto-closes this issue on merge, which auto-flips the corresponding checkbox on the parent tracker (#17809).