Drop stable/havana changes from official channels

As the stable/havana branches of official projects are being
deleted, there's no point in having these branches in the
announcement filters for those channels any longer. Note that this
does not remove it from unofficial/stackforge projects which may
still be using those branch names for other purposes.

Change-Id: If3bdc15ab1f0bb73138de1bdf735a5f3318579ab
Merge "Drop stable/havana changes from official channels"