The favicon should ideally change for self-hosted organizations if they
have configured it. We track the work for this in #35681 to look at
after the cutover.
We are starting the cutover process and starlight_help is the directory
we have agreed on to place our new help center project. We do not want
to use `starlight_help` as the URL for the project, but this commit
changes the url from `help-beta` to `starlight_help` temporarily since
we can only change URL once we get rid of the current help center
project. That will be done in a future commit.
