when using "Cross-cluster Data Migration Tool" , not disable compaction may cause be crash

[Jay-ju]

Steps to reproduce the behavior (Required)

if not set ADMIN SET FRONTEND CONFIG("lake_compaction_max_tasks"="0"); will cause be crash

Expected behavior (Required)

Real behavior (Required)

StarRocks version (Required)

• You can get the StarRocks version by executing SQL select current_version()

[xiangguangyxg]

It‘s required to disable compaction when migrating to a shared-data cluster now. We're also working on not having to disable compaction in the future.