[Bug] Can't split bundle: The size of split boundaries is not 1 - when using flow_or_qps_equally_divide

### Search before asking

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

### Version

v3.2.0

### Minimal reproduce step

Using the `flow_or_qps_equally_divide` bundle split algorithm with following config:
```
defaultNumberOfNamespaceBundles: "9"
defaultNamespaceBundleSplitAlgorithm: "flow_or_qps_equally_divide"
loadBalancerNamespaceBundleMaxMsgRate: "250"
```
Bundles are not split when multiple `splitBoundary` are returned by the algorithm:
https://github.com/apache/pulsar/blob/v3.2.0/pulsar-broker/src/main/java/org/apache/pulsar/common/naming/FlowOrQpsEquallyDivideBundleSplitAlgorithm.java#L50-L128

```
2024-03-05T12:56:26,943+0000 [pulsar-load-manager-1-1] INFO org.apache.pulsar.broker.loadbalance.extensions.strategy.DefaultNamespaceBundleSplitStrategyImpl - Splitting bundle: pinger/v2.0.0/0xaaaaaaa8_0xc71c71c4. Topics: 54/1000, Sessions: (125+51)/1000, Message Rate: 2077.90/250 (msgs/s), Message Throughput: 2.19/100 (MB/s)
2024-03-05T12:56:26,945+0000 [pulsar-load-manager-1-1] WARN org.apache.pulsar.broker.loadbalance.extensions.strategy.DefaultNamespaceBundleSplitStrategyImpl - Can't split broker:pinger/v2.0.0/0xaaaaaaa8_0xc71c71c4. The size of split boundaries is not 1. splitBoundary:[3211714940, 3266565899]
```

### What did you expect to see?

The bundle is split into multiple bundles at the returned boundaries.

### What did you see instead?

Bundles are not split at all and the above mentioned warning is logged by this condition:
https://github.com/apache/pulsar/blob/v3.2.0/pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/extensions/strategy/DefaultNamespaceBundleSplitStrategyImpl.java#L255-L260
It looks like the actual splitting code would work even with multiple split boundaries returned, so I'm wondering why this condition is there in the first place?

### Anything else?

I was able to execute the split manually by running:
```
bin/pulsar-admin namespaces split-bundle --bundle 0xaaaaaaa8_0xc71c71c4 --split-boundaries 3169176886 -san specified_positions_divide
```
After this, subsequent splits were done automatically again.

### Are you willing to submit a PR?

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