A while back we added a "StatsReporter" argument to `controller.NewImpl`,
but in serving every callsite of this is passing:
```
controller.NewImpl(r, logger, "my-string", MustNewStatsReporter("my-string", logger))
```
Where `MustNewStatsReporter` is just a form of knative/pkg's `controller.NewStatsReporter`
that logs fatally when an error is returned. It is notable that Serving's logic has been
duplicated to both Build and Eventing.
There are a handful of changes here:
1. Move MustNewStatsReporter into knative/pkg
2. Expose the current interface as NewImplWithStats
3. Drop the StatsReporter from NewImpl and default to `MustNewStatsReporter()`
This is a breaking change for downstream repositories, but should make their callsites universally simpler.
* split and update
* bug fixed
* change the copyright year
* use fake metadata in tests
* exclude test coverage for gcp_metadata
* add record
* add tests
* revert 2019 and add a new var
* change documents
* address comment
* change line
* Use different reporting periods based on the metrics backend. Original implementation was setting this value to 1 min to accommodate the minimum allowed value for stackdriver, but that is a sub optimal behavior for Prometheus. The change also allows operator to override the default values.
* Fix the units of reconciler latency from nano seconds to milliseconds.
* Address PR comments.
* Add better logging for reconciliation.
* Remove unnecessary lock in the UT.
* Address PR comments.