[Bug] The topic message storageSize is 0, Cannot skip msgBacklog for consumer

### Search before asking

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

### Version

2.9.3

### Minimal reproduce step

The commands clear-backlog, skip-all, skip --count do not skip the msgBacklog

### What did you expect to see?

skip msgBacklog for consumer

### What did you see instead?



![Uploading image.png…]()

### Anything else?

Topic Message TTL set 43200 secnons

### Are you willing to submit a PR?

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

Reproduce the issue on Pulsar 2.9.3 with a topic TTL of 43,200 seconds, then run clear-backlog, skip-all, and skip --count against a consumer. Trace the consumer backlog and message storageSize handling; done means these commands skip the msgBacklog as expected and a regression test covers the behavior.

Written by the indexing model from the issue text.