[Bug] Brokers can't reach balanced state sometimes when using UnifromLoadShedder

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Version

2.10.5

### Minimal reproduce step

1. Start 3 brokers and create some topics
2. Start producing and consuming for all these topics
3. Enable load balance with Uniformloadshedder:
- loadBalancerMsgThroughputMultiplierDifferenceShedderThreshold=1.1
- loadBalancerMsgRateDifferenceShedderThreshold=0, means disable msgRate based shedding
5. Use the default loadBalancerLoadPlacementStrategy `org.apache.pulsar.broker.loadbalance.impl.LeastLongTermMessageRate`
6. Restart brokers several times to trigger the load balance
7. There is a chance to see brokers can't reach the balanced state for long time.

### What did you expect to see?

All brokers should reach a balanced state after rounds of shedding.

### What did you see instead?

Brokers may stay in an un-balanced state for a long time.

### Anything else?

_No response_

### Are you willing to submit a PR?

- [X] I'm willing to submit a PR!