feat(meta): do configuration change in single barrier

[wenym1]

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What's changed and what's your intention?

Finalize and resolve #18312.

In this PR, we will

• Change to run all barrier manager commands with a single barrier, and the previous pause-change-resume mechanism will be removed.
• The PausedReason will be removed, and the pause and resume command will not hold a PausedReason
• We won't stop inject barrier when there is an inflight pause barrier
• The wait_epoch_committed rpc will be removed
• Newly created actors during configuration will start working immediately instead of pause on bootstrap.

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.
• My PR contains critical fixes that are necessary to be merged into the latest release.

Documentation

• My PR needs documentation updates.

Release note

[gru-agent]

❌ Rebase test pr failed: Error: Pull request #20493 is not created by gru-agent[bot]

[wenym1]

• feat(meta): do configuration change in single barrier #20493 👈 (View in Graphite)
• fix(log-store): rebuild decoupled sink on scale to fix data loss #20615
• main

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