PageStorage: unstable rename test in ut and mock tests

[JaySon-Huang]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Introduce by #5739

After #5739, we should not call shutdown for a table but later restore the DeltaMergeStore instance without restoring the global PageStorage instance. Cause store->shutdown will remove the callbacks, also clean the external ids ptrs from PageStorage. After restoring the DeltaMergeStore from disk without restoring the global PageStorage instance, it will run into removing all dtfiles from disk.

2. What did you expect to see? (Required)

3. What did you see instead (Required)

https://ci.pingcap.net/blue/organizations/jenkins/tiflash-ghpr-integration-tests/detail/tiflash-ghpr-integration-tests/8532/pipeline/194

4. What is your TiFlash version? (Required)

927b52f