refactor(snapshot-backfill): extract common logic of consuming snapshot and log store

[wenym1]

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What's changed and what's your intention?

Part of #19720.

For snapshot backfill, in the main branch and the future PR #19720, the stage of consuming snapshot and consuming log store have the similar logic of consuming a stream of row with op and convert the stream into stream chunk. In this PR, we will extra the common logic and let them share the same code.

Previously, the row streams of multiple vnodes are combined in the stream returned from StorageTable method. In this PR we will change to combine the stream of multiple vnodes outside StorageTable with FuturesUnordered, so that we can access each vnode stream and get the progress of each vnode, which will be useful in #19720.

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.

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Release note

[wenym1]

• feat(snapshot-backfill): introduce state to snapshot backfill #19720
• refactor(snapshot-backfill): extract common logic of consuming snapshot and log store #19936 👈 (View in Graphite)
• feat(storage): lazily remove instance data in uploader to avoid data loss #19931
• main

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