*: further adaptation to PD HTTP client

[JmPotato]

What problem does this PR solve?

Issue Number: ref #35319, tikv/pd#7300. Should merge after tikv/pd#7371.

Problem Summary:

What is changed and how it works?

• Remove pkg/util/pdapi package.
• Further integrate with the PD HTTP client.

Check List

Tests

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

Release note

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

None

[codecov]

Codecov Report

Merging #48606 (5bc4574) into master (ab354f3) will increase coverage by 1.8806%.
Report is 14 commits behind head on master.
The diff coverage is 43.2000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #48606        +/-   ##
================================================
+ Coverage   71.0747%   72.9553%   +1.8806%     
================================================
  Files          1365       1388        +23     
  Lines        404155     412403      +8248     
================================================
+ Hits         287252     300870     +13618     
+ Misses        96945      92734      -4211     
+ Partials      19958      18799      -1159     

Flag	Coverage Δ
integration	43.5562% <10.6557%> (?)
unit	71.3825% <43.2000%> (+0.3078%)	⬆️

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

Components	Coverage Δ
dumpling	53.9874% <ø> (ø)
parser	∅ <ø> (∅)
br	48.8869% <51.6129%> (-4.2184%)	⬇️

[JmPotato]

/test unit-test

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/test unit-test

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[JmPotato]

/retest

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-11-15 13:26:46.911562709 +0000 UTC m=+4255604.498672855: ☑️ agreed by hawkingrei.
• 2023-11-17 05:36:32.574340707 +0000 UTC m=+4400190.161450853: ☑️ agreed by tangenta.

[YuJuncen]

rest lgtm

[JmPotato]

/retest-required

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, lichunzhu, tangenta, YuJuncen

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Needs approval from an approver in each of these files:

• OWNERS [YuJuncen,hawkingrei,lichunzhu,tangenta]
• br/OWNERS [YuJuncen]
• br/pkg/lightning/OWNERS [lichunzhu]
• pkg/domain/OWNERS [tangenta]
• pkg/infoschema/OWNERS [tangenta]

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