[core] Improve error message for concurrent snapshot expiration

[yunfengzhou-hub]

Purpose

This PR adds a more detailed error message to the snapshot expiration process, showing users a possible cause of the FileNotFoundException they may face and the recommended solution to it.

Tests

A UT has been added to verify the error message in case of concurrent snapshot expiration.

API and Format

This PR does not affect API or format.

Documentation

This change does not need documentation

[yunfengzhou-hub]

Hi @tsreaper could you please take a look at this PR?

[wwj6591812]

+1