chore: owlbot copy google-cloud-workflows

[JoeWang1127]

Copy google-cloud-workflows from googleapis-gen, added librarian.js to fix index.ts and remove unused clients.

googleapis commit (same as the one in librarian.yaml).
googleapis-gen commit.

Step to copy the code:

docker run --rm --user $(id -u):$(id -g) -v .:/repo -w /repo -v ../googleapis-gen:/googleapis-gen --env HOME=/tmp gcr.io/cloud-devrel-public-resources/owlbot-cli:latest copy-code  --source-repo=/googleapis-gen --config-file=packages/google-cloud-workflows/.OwlBot.yaml

docker run --rm --user $(id -u):$(id -g) -v $(pwd):/repo -w /repo   --env HOME=/tmp   gcr.io/cloud-devrel-public-resources/owlbot-nodejs-mono-repo:latest packages/google-cloud-workflows

For googleapis/librarian#6278

[gemini-code-assist]

Code Review

This pull request introduces the auto-generated WorkflowsClient for both v1 and v1beta versions of the Google Cloud Workflows service, along with their corresponding configurations, tests, and updated documentation. The code review feedback highlights critical issues with the entry point files: the main src/index.ts contains duplicated imports and exports of v1 and v1beta which will cause TypeScript compilation failures, and the newly added WorkflowsClient is not exported from src/index.ts, v1/index.ts, or v1beta/index.ts. The reviewer recommends addressing these missing and duplicated exports upstream in the generator or templates to prevent them from being overwritten in future regenerations.