Remove `merge` workflow and update `build-and-publish-docs` workflow to be manually runnable

[austin-denoble]

Problem

Currently, we have a couple different GitHub workflows which deal with building and publishing the client reference documentation:

• merge.yaml
• build-and-publish-docs.yaml

merge calls build-and-publish-docs on every merge to main. This is problematic as any changes that are made which change documentation will be reflected at in the Python client reference as soon as they are merged to main even if we haven't cut a release.

Solution

• Remove the merge.yaml workflow entirely. Previously it was only dealing with building and deploying the reference docs.
• Update build-and-publish-docs to be a manually runnable or callable from another workflow.

For now, we can manually trigger new reference docs builds as needed, most likely after we cut a release. This isn't the best solution, but I think it's important to get this process out of the merge action, and we can iterate on it later.

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [X] Infrastructure change (CI configs, etc)
• [X] Non-code change (docs, etc)
• [ ] None of the above: (explain here)

Test Plan

Make sure nothing is triggered on merge to main.