Introduce a ScannerStartupDelay configuration to enable WAL write-only
recovery, allowing fence messages to be persisted during
primary–secondary switchover when the StreamingNode is trapped in crash
loops.
issue: https://github.com/milvus-io/milvus/issues/46368
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added a configurable WAL scanner pause/resume and a consumer request
flag to optionally ignore pause signals.
* **Metrics**
* Added a scanner pause gauge and pause-duration tracking for WAL
scanning.
* **Tests**
* Added coverage for pause-consumption behavior and cleanup in stream
client tests.
* **Chores**
* Consolidated flush-all logging into a single field and added a helper
for bulk message conversion.
<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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Signed-off-by: bigsheeper <yihao.dai@zilliz.com>
1. Fix primary-secondary replication switchover blocking by delete
replicate pchannel meta using modRevision.
2. Stop channel replicator(scanner) when cluster role changes to prevent
continued message consumption and replication.
3. Close Milvus client to prevent goroutine leak.
4. Create Milvus client once for a channel replicator.
5. Simplify CDC controller and resources.
issue: https://github.com/milvus-io/milvus/issues/44123
---------
Signed-off-by: bigsheeper <yihao.dai@zilliz.com>
Related to #44620
The test was flaky because pendingMessages.Len() assertion happened
before async message processing completed. Changed to assert.Eventually
to wait up to 1 second for the pending queue to drain, fixing the race
condition where actual was 1 but expected was 0.
Fixes TestReplicateStreamClient_Reconnect flakiness.
Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>
