[Enhancement] Make cursor caching eligibility logic reactive since reads don't get cached until checkCursorsToCacheEntries has been called

### Search before asking

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

### Motivation

Currently broker cache doesn't cache entries until `checkCursorsToCacheEntries` has been called. It get called as part of PulsarStats.updateStats which gets called every `statsUpdateFrequencyInSecs` (60s by default).
This could be a problem when a topic gets assigned to a broker and a large number of consumer connect in a large fanout scenario. The read request deduplication solution (PendingReadsManager added in #17241) will handle the problem for consumers at the same point of consumption, but caching would be useful for consumers that are not consuming exactly at the same location.

### Solution

Improve the cursor caching eligibility logic to be reactive instead of calculated every 60s.

### Alternatives

_No response_

### Anything else?

discussion thread about broker cache design: https://lists.apache.org/thread/xm095hnjo0cffbdy8ckysmzzm90gsbnp
broker cache default tuning: #23466

### Are you willing to submit a PR?

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