Add internal noop job

It does nothing.  Successfully.

This can be used in cases where a gate pipeline is required to
merge changes, but a project has no jobs to run.  This will
run a fake internal job that succeeds without wasting any worker
resources.

Change-Id: Ica0d109aaae5fd9aff6485eaba9c428491f98c60
Merge "Add internal noop job"