feat(stream,dashboard): improve actor input buffer blocking metrics and add actor busy time panel

[kwannoel]

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What's changed and what's your intention?

Checklist

• I have written necessary rustdoc comments.
• I have added necessary unit tests and integration tests.
• I have added test labels as necessary.
• I have added fuzzing tests or opened an issue to track them.
• My PR contains breaking changes.
• My PR changes performance-critical code, so I will run (micro) benchmarks and present the results.
• I have checked the Release Timeline and Currently Supported Versions to determine which release branches I need to cherry-pick this PR into.

Documentation

• My PR needs documentation updates.

Release note

[kwannoel]

• feat(stream,dashboard): improve actor input buffer blocking metrics and add actor busy time panel #23612 👈 (View in Graphite)
• main

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