This change updates the prometheus alerting rules to use ranged vectors
in their expressions, to avoid situations wher missed scrapes would
cause scalar metrics to "go stale" - resetting the alert timer.
Only the ceph alerts are affected by this change.
Change-Id: Ib47866d12616aaa808e6a09c58aa4352e338a152
Co-Authored-By: Meghan Heisler <mkheisler93@gmail.com>
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