HDDS-14749. Run update-ozone-site-config-doc after generate-config-doc

[adoroszlai]

What changes were proposed in this pull request?

• update-ozone-site-config-doc currently only runs if full CI succeeds, so website update can be delayed by intermittent failures. It should run after successful generate-config-doc, since it does not depend on tests.
• Rename the generate job in generate-config-doc to clarify its name within the CI workflow:
• Move some variable definitions to env from run block.

https://issues.apache.org/jira/browse/HDDS-14749

How was this patch tested?

• Full CI in fork, but update-ozone-site-config-doc is skipped due to conditions.
• Temporary tweaks to trigger update-ozone-site-config-doc in fork:
  • removed conditions
  • added debug output for event attributes with which the PR body is generated:

    workflow: build-branch
    run_id: 22547417135
    ref_name: HDDS-14749-test
    sha: 6685253f722cc96558a1cb127498859728c7b86f
    

[sarvekshayr]

Thanks for the much-needed improvements @adoroszlai. LGTM.

[sarvekshayr]

nit: This comment can be removed.

[adoroszlai]

Thanks @sarvekshayr for reviewing and merging this.