operator: make additional information thread safe

[HuSharp]

What problem does this PR solve?

Issue Number: Close #8079

What is changed and how does it work?

before #8032 merged(affected 8.1.0), controller has a lock https://github.com/tikv/pd/pull/8032/files#diff-0962f2eb6ba371d4f7abb601fdd9391aec93e770f1b75cad36045f86dea9b7d2L57

when cancel the operator, will hold this lock to avoid data race.

• We need to make sure the additional information field is safe
• other fields only be set when createOperator

panic get from the array while inserting elements in this array

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• nolouch

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[codecov]

Codecov Report

Merging #8104 (6a9906b) into master (882d2e5) will increase coverage by 0.01%.
Report is 2 commits behind head on master.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8104      +/-   ##
==========================================
+ Coverage   77.28%   77.30%   +0.01%     
==========================================
  Files         470      470              
  Lines       61129    61143      +14     
==========================================
+ Hits        47244    47264      +20     
+ Misses      10310    10309       -1     
+ Partials     3575     3570       -5     

Flag	Coverage Δ
unittests	77.30% <100.00%> (+0.01%)	⬆️

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[nolouch]

/merge

[ti-chi-bot]

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[ti-chi-bot]

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

Commit hash: 6a9906b

[nolouch]

/run-cherry-picker

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #8111.