feat enhance : Ignore specified unhealthy tables during load balancing.

[ruojieranyishen]

background

The current blacklist feature allows ignoring some apps during the load balancing process. However, a drawback is that load balancing is triggered only when all partitions are healthy.

Goals

If all unhealthy apps are in the blacklist, load balancing can still start.

Solution

1. Modifiy load balancing start condition.
2. Refactor the existing blacklist, and only transfer the required apps to the load balancer.
3. Add unit tests.