Re-enable memory_tracker

The old peakmem_tracker service has been disabled in [0], now enable
the replacement memory_tracker.

Also fail when the old service is still configured, otherwise
consumers might never notice.

Depends-On: https://review.opendev.org/739995
Change-Id: I583caf3f36a8ff41d7d4106dabc6c5f24243085e
2 files changed