Add metrics to replicated metadata store

[tillrohrmann]

In order to not fly entirely blind when using the replicated metadata server, we should add some basic metrics. Some ideas could be:

• Bytes written/read
• Size of write requests
• Latency for read/write requests
• Uncommitted raft log length
• Number of rejected writes because of precondition violation

[lsytj0413]

/assign

[lsytj0413]

I want to confirm what metrics should be add, currently there is

• restate.metadata_server.replicated.sent_messages.bytes
• restate.metadata_server.replicated.received_messages.bytes
• restate.metadata_server.get.duration
• restate.metadata_server.put.duration

ans so on in https://github.com/restatedev/restate/blob/main/crates/metadata-server/src/metric_definitions.rs , what else need to add？

[tillrohrmann]

I think this issue has been superseded by https://github.com/restatedev/restate/issues/2605 and we can close it. Sorry for not properly maintaining it @lsytj0413.