chore: regenerate libraries with gapic-generator @ 78ff458

[daniel-sanche]

In the style of #18243, updates the generator version and regenerates code using the following commands:

pip install <path to gapic-generator @ commit faa0f81>
V=$(go run github.com/googleapis/librarian/cmd/librarian@latest config get version)
go run github.com/googleapis/librarian/cmd/librarian@${V} install
go run github.com/googleapis/librarian/cmd/librarian@${V} generate -v --all

This PR also disables autom-ml smoke tests, as the backend has been deprecated. This change is taking place across languages

BEGIN_COMMIT_OVERRIDE
feat: declare Python3.15 support
END_COMMIT_OVERRIDE

[gemini-code-assist]

Code Review

This pull request updates the librarian.yaml configuration to use a newer version of gapic-generator. Additionally, across numerous Google Cloud and Google Ads Python packages, it updates noxfile.py to include UNIT_TEST_DEPENDENCIES in the unit test environment installation, and updates setup.py to add the classifier for Python 3.15. There are no review comments, so I have no feedback to provide.