fix pagestorage v2 restore (#5384)

[ti-chi-bot]

This is an automated cherry-pick of #5384

What problem does this PR solve?

Issue Number: close #5385

Problem Summary: When restart, ps v2 will try to reuse old page file for writing. But if no file can be used for writing, it will create new page file. But the file id of the new page file is determined by the max file id in writing page file set which is empty now. And it will create PageFile_1_0 in this case for writing which may override previous data.

What is changed and how it works?

Make sure new page file id is larger than all current page files at restart.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JaySon-Huang
• lidezhu

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[lidezhu]

/rebuild

[ti-chi-bot]

This pull request is closed because its related version has closed automatic cherry-picking.
If it's still needed, you can reopen it or just regenerate it using bot,
see:

https://prow.tidb.net/command-help#cherrypick
https://book.prow.tidb.net/#/plugins/cherrypicker