Remove grizzly jobs and job filters

Any grizzly-specific jobs and filters which prevent jobs from being
run on stable/grizzly branches are removed, but this should not be
merged until all stable/grizzly proposed changes have been abandoned
and corresponding branches tagged and deleted.

Change-Id: I39f93f67b96961cd9991b6a13fecddb16e3a20fa
Merge "Remove grizzly jobs and job filters"