[Bug] Consumption unevenness arises in the consumption performance pressure test.

### Search before reporting

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

### Read release policy

- [x] I understand that [unsupported versions](https://pulsar.apache.org/contribute/release-policy/#supported-versions) don't get bug fixes. I will attempt to reproduce the issue on a supported version of Pulsar client and Pulsar broker.

### User environment

3.0.10
jdk17
client 3.0.10

### Issue Description

When conducting consumption performance pressure tests with a relatively large number of consumers per partition (over 1000), consumption imbalance will occur: the consumption speed of some partitions drops significantly, the overall throughput declines, and message backlog eventually arises in certain partitions.

### Error messages

```text
no error
```

### Reproducing the issue

When conducting consumption performance pressure tests with a relatively large number of consumers per partition (over 1000), consumption imbalance will occur: the consumption speed of some partitions drops significantly, the overall throughput declines, and message backlog eventually arises in certain partitions.

### Additional information

_No response_

### Are you willing to submit a PR?

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

No source files, tests, or entry points are named. Start by reproducing the consumption performance pressure test on Pulsar 3.0.10 with JDK 17 and more than 1,000 consumers per partition, then compare partition consumption rates, overall throughput, and backlog growth. Done means the reported consumption imbalance is understood and corrected, with the pressure test no longer showing stalled partitions.

Written by the indexing model from the issue text.