[Issue] The throttling is not exact for both publish and dispatch in pulsar-2.10.1 version

### Search before asking

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

### Version

pulsar-2.10.1 runs on the k8s cluster.

### Minimal reproduce step

## Precondition
There is only one topic under this namespace.
Topic: `persistent://kafka_test/test/my_test_par_10`
Partition Num: 10
Broker Num: 3
Bookie Num: 4
Broker Metrics: `pulsar_throughput_in`, `pulsar_throughput_out`

### Producer
`bin/pulsar-perf produce --batch-max-messages 30000 --num-producers 2 --num-test-threads 2 --num-io-threads 2 --rate 30000 --size 1000 persistent://kafka_test/test/my_test_par_10`

### Consumer
`bin/pulsar-perf consume persistent://kafka_test/test/my_test_par_10 -ss sub201`

## Dispatch Rate Test
Please refer to [PIP-3](https://github.com/apache/pulsar/wiki/PIP-3:-Message-dispatch-throttling)
We test the byte and message dispatch rates separately. The test results are not excepted(Not exact).

### Byte Dispatch Rate
Only set the byte dispatch rate = 1000000(1MB). The excepted result is 1MB/s. However, the test result is 11.9MB/s.(Ref to broker metric `pulsar_throughput_out `)
`bin/pulsar-admin namespaces set-dispatch-rate kafka_test/test --byte-dispatch-rate 1000000 --dispatch-rate-period 1`

### Message Dispatch Rate
Only set the message dispatch rate = 1000. The excepted result is 1MB/s. However, the test result is 12.5MB/s.(Ref to broker metric `pulsar_throughput_out `)
`bin/pulsar-admin namespaces set-dispatch-rate kafka_test/test --msg-dispatch-rate 1000 --dispatch-rate-period 1`

## Publish Rate Test
We test the byte and message publish rates separately. The test results are not excepted.

### Byte Publish Rate
Only set the byte publish rate = 1000000(1MB). The excepted result is 1MB/s. However, the test result is 8.9MB/s.(Ref to broker metric `pulsar_throughput_in `)
`bin/pulsar-admin namespaces set-publish-rate kafka_test/test --byte-publish-rate 1000000`

### Message Publish Rate
Only set the message publish rate = 1000. The excepted result is 1MB/s. However, the test result is 8.8MB/s.(Ref to broker metric `pulsar_throughput_in `)
`bin/pulsar-admin namespaces set-publish-rate kafka_test/test --msg-publish-rate 1000`

## Resource Group
Please refer to [PIP-82](https://github.com/apache/pulsar/wiki/PIP-82:-Tenant-and-namespace-level-rate-limiting)
I tested both publish rate and dispatch rate in resourcegroup. However, the test results show the sourcegroup throttling does not work exactly.

## Publish Rate

### Message Publish Rate
Only set the message publish rate = 100. One message size = 1024. The excepted result is 100KB/s. However, the result is 14.7MB/s.
```
bin/pulsar-admin resourcegroups create rs_name --msg-publish-rate 100
bin/pulsar-admin namespaces set-resource-group kafka_test/test --resource-group-name rs_name
```

### Byte Publish Rate
Only set the byte publish rate = 10000(1MB). One message size = 1024. The excepted result is 10KB/s. However, the result is 11MB/s.
```
bin/pulsar-admin resourcegroups create rs_name --byte-publish-rate 10000
```

## Dispatch Rate

### Byte Dispatch Rate
Only set the byte dispatch rate = 1000(1MB). One message size = 1024. The excepted result is 10KB/s. However, the result is 20MB/s.
```
bin/pulsar-admin resourcegroups create rs_name --byte-dispatch-rate 10000
```

### Message Dispatch Rate
Only set the message dispatch rate = 100. One message size = 1024. The excepted result is 100KB/s. However, the result is 21.2MB/s.
```
bin/pulsar-admin resourcegroups create rs_name --msg-dispatch-rate 100
```

### What did you expect to see?

I provide the excepted value in the above reproduction steps.

### What did you see instead?

Please refer to the reproduction steps.

### Anything else?

_No response_

### Are you willing to submit a PR?

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

Start by reproducing the issue with the provided pulsar-perf producer and consumer commands, then apply the namespace and resource-group limits through the listed pulsar-admin commands. Compare broker metrics with the configured byte and message limits; done means publish and dispatch throughput is close to the expected values rather than several times higher.

Written by the indexing model from the issue text.