server: add metrics server interceptor to DRPC

[shubhamdhama]

In cockroachdb/drpc#10, we added the DRPC framework level support for interceptors. This PR ports the metrics interceptor to DRPC server.

Epic: CRDB-49359
Release note: None
Fixes: #144373

[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

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[cockroach-teamcity]

This change is 

[shubhamdhama]

Couple of improvements are needed here,

1. Decide whether we really need a separate metric for DRPC. The other options here are: Reuse the existing metric and add another dimension rpcServer with two possible values drpc and grpc. Or, neither of them, reuse the same metric as it is.
2. Deduplication of code

[shubhamdhama]

Closing in favor of #153651