Doris support deploy multi BE on one host. So when allocating BE for replicas of
a tablet, we should select different host. But there is a bug in tablet scheduler
that same host may be selected for one tablet. This patch will fix this problem.
There are some places related to this problem:
1. Create Table
There is no bug in Create Table process.
2. Tablet Scheduler
Fixed when selecting BE for REPLICA_MISSING and REPLICA_RELOCATING.
Fixed when balance the tablet.
3. Colocate Table Balancer
Fixed when selecting BE for repairing colocate backend sequence.
Not fix in colocate group balance. Leave it to colocate repairing.
4. Tablet report
Tablet report may add replica to catalog. But I did not check the host here,
Tablet Scheduler will fix it.
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