KAFKA-13392 Resolve Timeout Exception triggering reassign partitions with --bootstrap-server option

[Hongten]

This PR resolved the timeout exception triggering reassign partitions with --bootstrap-server option. More can be found https://issues.apache.org/jira/browse/KAFKA-13392.

Root cause
When we run a reassignment using a plan file (e.g. xxx.json), the plan may still include replicas on the down broker. During the execution, we try to apply throttling by calling adminClient.incrementalAlterConfigs(configs). The issue is: this API needs to connect to the target broker to set the broker-level throttle configs.
If the broker is down, it’s obviously unreachable, so the client keeps retrying and eventually times out → TimeoutException.

My proposed solution
Add a new parameter: --broker-list-without-throttle
Description: Optional. Comma-separated broker ID list (e.g. 1,2) that should be excluded from broker-level throttle config updates during partition reassignment execution. When --execute and --throttle are used, it normally applies throttle configs on all brokers involved in the reassignment. If any of those brokers are known to be down or unreachable, adding them to --broker-list-without-throttle makes it skip the throttle-setting step for those brokers, avoiding retries/timeouts, while still throttling the remaining reachable brokers.
Value: a list of broker IDs, comma-separated
Example: 1001 or 1001,1002

  --bootstrap-server xxx.xxx.xxx.xxx:9092 \
  --reassignment-json-file reassignment-test.json \
  --throttle 209715200 \
  --execute \
  --broker-list-without-throttle 1001

If broker 1001 is known to be down, and the reassignment plan includes it, then we exclude 1001 from throttle config changes.

Why this is needed

• If we don’t use '--throttle' at all, then Kafka won’t set throttle on any broker (including the down one). But that’s risky, migrations can easily blow up network bandwidth or disk IO.
• If we only skip throttling for the known down broker, it doesn’t change the reassignment logic itself, and it avoids the timeout. Meanwhile, healthy brokers still get throttled properly.

[Hongten]

cc @mimaison @chia7712 @showuon This PR is ready for review, please take a look when you get a moment. thanks.:)

[lianetm]

this is adding a new param to a command line tool (public API), so it would need a KIP to discuss and approve with the community. You can find info here and take it from there https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Improvement+Proposals#KafkaImprovementProposals-Process
Thanks for looking into this!