* add metrics and tracing to state manager
* propagate tracer to state manager
* add scheduler metrics
* fix backtesting
* add test for state metrics
* remove StateUpdateCount
* update docs
* metrics can be null
* add tracer to new tests
This commit adds support for concurrent queries when saving alert
instances to the database. This is an experimental feature in
response to some customers experiencing delays between rule evaluation
and sending alerts to Alertmanager, resulting in flapping. It is
disabled by default.
* Create historian metrics and dependency inject
* Record counter for total number of state transitions logged
* Track write failures
* Track current number of active write goroutines
* Record histogram of how long it takes to write history data
* Don't copy the registerer
* Adjust naming of write failures metric
* Introduce WritesTotal to complement WritesFailedTotal
* Measure TransitionsFailedTotal to complement TransitionsTotal
* Rename all to state_history
* Remove redundant Total suffix
* Increment totals all the time, not just on success
* Drop ActiveWriteGoroutines
* Drop PersistDuration in favor of WriteDuration
* Drop unused gauge
* Make writes and writesFailed per org
* Add metric indicating backend and a spot for future metadata
* Drop _batch_ from names and update help
* Add metric for bytes written
* Better pairing of total + failure metric updates
* Few tweaks to wording and naming
* Record info metric during composition
* Create fakeRequester and simple happy path test using it
* Blocking test for the full historian and test for happy path metrics
* Add tests for failure case metrics
* Smoke test for full annotation persistence
* Create test for metrics on annotation persistence, both happy and failing paths
* Address linter complaints
* More linter complaints
* Remove unnecessary whitespace
* Consistency improvements to help texts
* Update tests to match new descs
