[improve] [broker] filter transaction_coordinator_assign while shedding

### Search before asking

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

### Motivation

Topics/Bundles will be unload while doing shedding, and there are some special topics that should not be unloaded for some reason. For example, if `transaction_coordinator_assign` is unloaded, the corresponding TC need to be recovered, which is time consuming.
So, we have better avoid unload these topics. And i found that such features have been implemented in the latest branch except branch-2.9.

### Solution

fitler system topics while shedding in branch-2.9.

### Alternatives

_No response_

### Anything else?

_No response_

### Are you willing to submit a PR?

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

Start by comparing branch-2.9's broker shedding implementation with the latest branch, where the issue says this behavior already exists. Trace how system topics are selected during shedding, then verify that transaction_coordinator_assign is filtered and is not unloaded during shedding.

Written by the indexing model from the issue text.