Bug 1370539 - Fix logic error around skipping package metrics; r=nalexander, a=RyanVM

b227363d66bb added a config item and code for disabling package
metrics, which don't work everywhere.

The previous logic was faulty.

MozReview-Commit-ID: BGxWgmWxXyH

Pushing on a CLOSED TREE

--HG--
extra : amend_source : 99ca472e4c0fca306deec4038e9c7cbfe5412b0a