`*RetryingCaller` doesn't set the underlying callable name for prometheus metrics

[spacesphere]

When using AsyncRetryingCaller (and RetryingCaller), callable name is not set properly as a label for the stamina_retries_total prometheus metric (like so stamina_retries_total{callable="<context block>",error_type=...}).

Shouldn't it work similar to the retry deco?

[hynek]

The reason is because the callable is not the point of retry here, but (implicitly) a context block. You could have more than one in one callable which would make guessing the name based on the frame ambiguous.

I think the only way forward here would be to add optional name metadata to *RetryingCaller and retry_context().