br: reset cloud_admin and root after ebs restoration (#39986)

[fengou1]

What problem does this PR solve?

Issue Number: close #40418

Problem Summary:

1. For ebs volume-snapshot restore, we need to reset some accounts otherwise db_initializer will fail due to accounts existing.

What is changed and how it works?

1. add a new config reset-sys-users. in case we need to reset more users in future.
2. remove cloud_admin by default
3. reset the root password and let cloud_admin control it.

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Leavrth
• joccau

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[joccau]

LGTM

[joccau]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: eebb004