add message strings to recheckwatchbot.yaml

This is done *before* the code is added to support this as for
CD deployment we need to land catalog first, then code changes
after the catalog is in place, otherwise we stop having working
messages entirely.

Change-Id: I159e07c233f636c9261ad0b204cf394f748243b3
Merge "add message strings to recheckwatchbot.yaml"