[server][dvc] Add blob transfer send/receive byte rate metric at both version level and host level

[sixpluszero]

[server][dvc] Add blob transfer send/receive byte rate metric at both version level and host level

This PR adds rate metric for blob transfer send and receive activity for more observability in the ingestion path.

It will give host level send/receive byte rate, as well as version level send/receive byte rate. With this, we can easily monitor how system is doing the blob transfer from/to other peer nodes.

Solution

Code changes

• Added new code behind a config. If so list the config names and their default values in the PR description.
• Introduced new log lines.
  • Confirmed if logs need to be rate limited to avoid excessive logging.

Concurrency-Specific Checks

Both reviewer and PR author to verify

• Code has no race conditions or thread safety issues.
• Proper synchronization mechanisms (e.g., synchronized, RWLock) are used where needed.
• No blocking calls inside critical sections that could lead to deadlocks or performance degradation.
• Verified thread-safe collections are used (e.g., ConcurrentHashMap, CopyOnWriteArrayList).
• Validated proper exception handling in multi-threaded code to avoid silent thread termination.

How was this PR tested?

• New unit tests added.
• New integration tests added.
• Modified or extended existing tests.
• Verified backward compatibility (if applicable).

Does this PR introduce any user-facing or breaking changes?

• No. You can skip the rest of this section.
• Yes. Clearly explain the behavior change and its impact.