use bugzilla-daemon as sender address for scripts

because the ones i just tried to fake run into
sender verification, f.e.:

550-Address bugzilla-metrics@wikimedia.org does not exist\n
550 Sender verify failed

and this one, bugzilla-daemon, already existed without
me having to add it, and uses :blackhole:

and these addresses should be "do-not-reply" anyways

Change-Id: If136b61e8b20e74e5d2d81b807c652e3f31b81df