fix: avoid panic when the file is corrupted in disk cache

[ShiKaiWi]

Rationale

• The corrupted file in the disk cache will lead to the panic of the server
• The whole cache page file is fetched when only a range of the file is accessed, leading to high memory consumption

Detailed Changes

• Store the file size in the memory for file integrity check
• Omit the corrupted file in the disk cache rather than panic
• Do IO operation outside the meta data cache lock
• Read only the involved range of a cached paged file instead of the whole file

Test Plan

Existing tests and a newly designed test.

[jiacai2050]

LGTM