cmd: Make changefeed sort dir visible (#2222)

[ti-chi-bot]

This is an automated cherry-pick of #2222

What problem does this PR solve?

This PR try to revert part of the work in #1784, also fix a problem when try to set data-dir by existed changefeed information.

• sort-dir can be read but cannot be written.
• create dir temporarily when try to find best data-dir by existed changefeed information.

What is changed and how it works?

revert changefeed info struct and related read and write.

Check List

Tests

• Unit test

Code changes

Side effects

Related changes

Release note

• No release note

[ti-chi-bot]

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[3AceShowHand]

/run-all-tests

[ti-chi-bot]

Merge canceled because a new commit is pushed.

[ti-chi-bot]

@ti-chi-bot: Your PR was out of date, I have automatically updated it for you.

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/run-all-tests

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[3AceShowHand]

/run-leak-tests

[3AceShowHand]

/merge

[ti-chi-bot]

@3AceShowHand: /merge is only allowed for the committers, you can assign this pull request to the committer in list by filling /assign @committer in the comment to help merge this pull request.

In response to this:

/merge

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[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.0@5d1554b). Click here to learn what that means.
The diff coverage is n/a.

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