Fix "Failed Publishing GitHub checks"

Happening in most jobs, e.g. jx-platform-builders:

[GitHub Checks] Failed Publishing GitHub checks: org.kohsuke.github.HttpException: {"message":"You must authenticate via a GitHub App.","documentation_url":"https://docs.github.com/rest/reference/checks#create-a-check-run"}

This error appeared at the beginning of June 2023, before that we used to have instead:

[Checks API] No suitable checks publisher found.

This is due to the GitHub Checks Plugin, installed with NXBT-3480.

It doesn't happen on jobs configured with GitHub app credentials for the GitHub Branch Sources configuration, e.g. nuxeo-java-client.

For the jobs configured with GitHub branch source credentials (most of the jobs), as documented here, let's configure the "Status Checks Properties" behavior in GitHub Branch Sources to "Skip publishing status checks".