Change metrics name or allow to configure prefix

[dpr-dev]

Is your feature request related to a problem? Please describe.
Hey, guys.
We encountered the following problem while configuring metrics for self hosted cluster. Metrics are not labeled with a special prefix, so there is no grouping for hundreds of metrics. This in turn makes it confusing, because it is not clear whose metrics they are exactly

The example on the screen from google cloud monitoring.

Describe the solution you'd like
It would be cool if all metrics could be grouped under a common label, like Temporal, TemporalWorker, TemporalPoll, etc, so as not to pollute the overall scope.

Describe alternatives you've considered
On the other hand, it's a pretty breakable change. It may be possible to specify a prefix through env variables, which will be empty by default (for backward compatibility), which anyone can specify and thus change the name of metrics in monitoring systems if desired