Bug 6926: Unify verify triggers and improve trigger words

Bug 6926: Unify verify triggers and improve trigger words

All patch-triggered jobs now ignore drafts and commit-message-only edits.
This is to prevent situations when only a subset of verify jobs is triggered,
as that could lead to false Verified+1.

Also, only 'recheck' now triggers all verify-type jobs.
Other words such as reverify, revalidate, redistcheck, retox, renode and redocs
only trigger one job, to save time when other job results are reliable.

Docs: Trigger words updated and distribution-check added.

Change-Id: I5769d7e4d148e01428de8b13747b1f04148e7581
Signed-off-by: Vratko Polak <vrpolak@cisco.com>