chore: migrate google-cloud-translate to librarian

[jskeet]

No description provided.

[gemini-code-assist]

Code Review

This pull request updates the configuration for the translate library. Specifically, it modifies librarian.yaml to replace skip_generate: true with a list of files to keep, deletes an unused configuration file, and updates the repository metadata in .repo-metadata.json by adding an API description, removing the billing requirement and codeowner team fields, and reformatting the JSON. There are no review comments, so I have no feedback to provide.

[jskeet]

Note that this has a keep list with three entries:

• src/v2/index.ts is preserved as the v2 client
• test/index.ts is preserved as a handwritten test for the v2 client
• src/index.ts is preserved as there is no way currently of generating it in combine-libraries; we want to effectively have a default version of v2, but that isn't a GAPIC client. In the BazelBot/OwlBot pipeline, this is implemented by skipping the file in https://github.com/googleapis/googleapis/blob/master/google/cloud/translate/BUILD.bazel:

nodejs_gapic_combined_pkg(
    name = "google-cloud-translate-nodejs",
    default_version = "v3",
    release_level = "stable",
    templates_excludes = ["package.json", "src/index.ts", ".OwlBot.yaml"],
    deps = [
        "//google/cloud/translate/v3:translation-v3-nodejs",
        "//google/cloud/translate/v3beta1:translation-v3beta1-nodejs"
    ],
)