Escalation emails should ignore obsoleted features.

[jstenback]

Describe the bug
Today we sent around a set of escalation emails for features that are about to ship in a Chrome release but whose data has not recently been verified. That set of emails included an escalation for an obsoleted feature, specifically this feature. The feature itself states it's only shown to those with edit access, so nothing to verify there. We should filter out obsoleted features in those escalation emails.