*: support to query init stats percentage from http api

[hawkingrei]

What problem does this PR solve?

Issue Number: close #53564

Problem Summary:

What changed and how does it work?

Add progress information in the status.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

➜  opensource curl http://127.0.0.1:9081/status
{"connections":0,"version":"8.0.11-TiDB-v8.3.0-alpha-129-g158199c87d","git_hash":"158199c87d9bb83e045e4e113d38d323006ea41d","status":{"init_stats_percentage":100}}

• No need to test

  • I checked and no code files have been changed.

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

[codecov]

Codecov Report

Attention: Patch coverage is 11.11111% with 16 lines in your changes missing coverage. Please review.

Project coverage is 70.5509%. Comparing base (b066365) to head (e710229).
Report is 1 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #55323        +/-   ##
================================================
- Coverage   74.7027%   70.5509%   -4.1519%     
================================================
  Files          1570       1570                
  Lines        364767     437229     +72462     
================================================
+ Hits         272491     308469     +35978     
- Misses        72509     108181     +35672     
- Partials      19767      20579       +812     

Flag	Coverage Δ
integration	48.7711% <11.1111%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	55.1894% <ø> (ø)
parser	∅ <ø> (∅)
br	57.8048% <ø> (+10.1871%)	⬆️

[lance6716]

/approve

for domain part

[lance6716]

/lgtm

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-09 05:11:07.427599603 +0000 UTC m=+587997.294698694: ☑️ agreed by winoros.
• 2024-08-09 07:12:04.637271943 +0000 UTC m=+595254.504371033: ☑️ agreed by lance6716.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lance6716, winoros

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Needs approval from an approver in each of these files:

• OWNERS [lance6716,winoros]
• pkg/domain/OWNERS [lance6716]
• pkg/statistics/OWNERS [winoros]

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