fix(stream): arrangement backfill should use dist key instead of pk to derive vnode

[kwannoel]

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What's changed and what's your intention?

The error seen will be (See the failing test here: https://buildkite.com/risingwavelabs/pull-request/builds/49863#018f9186-a50d-4f80-91d9-4ba0a30ca007):

failed to run `e2e_test/backfill/sink/different_pk_and_dist_key.slt`

Caused by:
    statement failed: db error: ERROR: Failed to run the query
    
    Caused by these errors (recent errors listed first):
      1: gRPC request to meta service failed: Internal error
      2: get error from control stream: worker node 1, gRPC request to stream service failed: Internal error: failed to collect barrier for epoch [6481195908136960, 6481195916460032, 6481195982061568]: Actor 38 exited unexpectedly: Executor error: Backfill progress for vnode VirtualNode(
        196,
    ) not found, backfill_state not initialized properly;
    

The fix is to just use dist_key instead of pk to derive the vnode when handling chunks coming from upstream. This is done with the state table's compute_vnode_by_pk interface. Under the hood, it will use the dist_key_indices_in_pk to extract the dist key from pk, and construct the vnode.

This will impact newly created MVs, when their dist_keys do not match their PKs.
The workaround is to set streaming_use_arrangement_backfill=false.

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[KeXiangWang]

LGTM. Thanks for the timely fix!

[chenzl25]

LGTM, thanks