Based on [OpenTelemetry Metrics gRFC](https://github.com/grpc/proposal/blob/master/A66-otel-stats.md#opentelemetry-metrics), we should recored unregistered RPC method name as `other`, this PR adds the ability to pass register method information when creating a call.
We'll consider calls created using generated stubs as registered, note that this won't prevent user from setting `registered_method=True` when creating calls manually.
This is also enabled for simple stub flow but **NOT enabled for AsyncIO**, we'll add that later when start working on AsyncIO Observability.
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Closes#35002
PiperOrigin-RevId: 596719121
9a7c0b5f57