Use cached branches on tenant reconfiguration

It takes about one minute for us to query gerrit for all the project
branches, so don't do that on tenant reconfiguration, except for
the project which prompted the reconfiguration (in case the event
was a branch creation or deletion).

Also, clean up some unused arguments to getProject methods.

Change-Id: I625dfc6af00d8d480fcb6bac5d0b86e4846844c0
1 file changed