Update references to GerritJenkinsGit wiki

We've moved the GerritJenkinsGithub wiki page to instead be
at GerritJenkinsGit, update references to it in our configs.

Change-Id: I88d8140a0e5f6e4051ca78415e0152c9cdcb86f6
Merge "Update references to GerritJenkinsGit wiki"