[Bug](load) INSERT SELECT data invisible after quorum success with cancelled node channel

[xiaobijuan2026]

Problem

When INSERT INTO ... SELECT ... writes to multiple replicas, if one node channel is slow and times out during close_wait, it gets cancelled but NOT marked as failed. This causes:

1. close_wait returns OK even though a node was cancelled
2. FE is unaware of the failure, commits the transaction
3. PUBLISH_VERSION task is sent to ALL nodes including the cancelled one
4. Cancelled node can't find the rowset → publish fails
5. Data stays COMMITTED but not VISIBLE for a long time (30+ minutes until retry)

Root Cause

In IndexChannel::close_wait() (vtablet_writer.cpp), when unfinished node channels are cancelled due to timeout, mark_as_failed() is not called. FE receives no error tablet info for the cancelled replicas.

Fix

After cancelling unfinished node channels in close_wait timeout:

1. Call mark_as_failed() to record failed tablets
2. Call check_intolerable_failure() - if failures exceed tolerance, fail the entire load
3. Call set_error_tablet_in_state() to propagate error info to FE

This allows FE to:

• Skip failed replicas during PUBLISH_VERSION
• Data becomes visible immediately on healthy replicas
• Background TabletScheduler auto-repairs the failed replica

Behavior after fix

Scenario	Replicas	Result
3 replicas, 1 timeout	2/3 success	✅ Publish succeeds, failed replica auto-repairs
3 replicas, 2 timeout	1/3 success	❌ Load fails, user gets error