Add ckb_block_process_duration in metric for monitoring and testing

[chenyukang]

What problem does this PR solve?

We need to monitor the time duration for process_block, this is useful to benchmark the new verify with pause, we want to compare the different results from develop branch and the new feature branch.

What is changed and how it works?

Add ckb_block_process_duration in matrics.

What's Changed:

Related changes

• PR to update owner/repo:
• Need to cherry-pick to the release branch

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code ci-runs-only: [ quick_checks,linters ]

Release note

None: Exclude this PR from the release note.