fix(sink): align init epoch for coordinated sinks

[wenym1]

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What's changed and what's your intention?

Resolve #19337

In coordinated sinks, different parallelisms coordinate with each other by their epoch progress. More specifically, they should write the data of the same epoch simultaneously, and then commit together on the epoch, and then write the same epoch truncate offset to storage. Since different parallelisms should work on the same epoch, we need to ensure that after recovery they are initialized from the same epoch. However, in sink log store, since we only need to ensure at-least-once delivery, the truncation offset set by log reader is not guaranteed to be applied and written to persistent storage. This works for normal sinks in which different parallelisms work independently. But for coordinated sink, it may happen that, for example, the truncate offset on epoch1 of parallelism1 is applied to storage, but on parallelism2, the offset is not applied. After recovery, parallelism1 will be initialized from the next epoch of epoch1, but parallelism2 will still be initialized from epoch1, and then the two parallelisms won't be initialized at the same epoch, and then cause error in #19337.

In this PR, we introduce a flag to KvLogStoreFactory named align_epoch_on_init. The flag will be set to true for coordinated sinks. When this feature is on, in initialization, we won't use left unbounded to read the historical stream. Instead, we will load the truncate offset globally from all vnodes from the committed snapshot, and use the latest truncate offset as the left bound to read historical stream. In the example above, parallelism2 can see that some other parallelisms have written truncate offset on epoch1, and then it will skip epoch1 and initialize from the next epoch, though itself never writes the truncate offset yet.

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[chenzl25]

LGTM!