Automate the process of cleaning up the Gerrit info we keep.
We query Gerrit server and check if review is merged or abandoned.
If so, we remove data from database and query Jenkins to remove
the related PPA.
Ideally this should not be needed but it seems there are some
cases/scenarios that we don't manage properly.
* will be executed each 15th day of the month at 7:30
* add timezone info to Gerrit fixtures to reduce warning
Change-Id: Ic5ddc3b646532257bd7747443a6fdead4ff28544