http: init NewDefaultPDServiceDiscovery and refine http client tests

[HuSharp]

What problem does this PR solve?

Issue Number: Close #7721

What is changed and how does it work?

Check List

Tests

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

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CabinfeverB
• JmPotato

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[HuSharp]

/test ?

[ti-chi-bot]

@HuSharp: The following commands are available to trigger required jobs:

• /test build

The following commands are available to trigger optional jobs:

• /test pull-integration-copr-test
• /test pull-integration-realcluster-test

Use /test all to run the following jobs that were automatically triggered:

• tikv/pd/ghpr_build

In response to this:

/test ?

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[HuSharp]

/test pull-integration-realcluster-test

[HuSharp]

/test pull-integration-realcluster-test

[codecov]

Codecov Report

Merging #7744 (680a92c) into master (2c8e21c) will decrease coverage by 0.68%.
The diff coverage is 75.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7744      +/-   ##
==========================================
- Coverage   73.84%   73.16%   -0.68%     
==========================================
  Files         430      430              
  Lines       47629    47630       +1     
==========================================
- Hits        35173    34850     -323     
- Misses       9487     9814     +327     
+ Partials     2969     2966       -3     

Flag	Coverage Δ
unittests	73.16% <75.00%> (-0.68%)	⬇️

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[HuSharp]

/test pull-integration-realcluster-test

[HuSharp]

/test pull-integration-realcluster-test

[JmPotato]

/test pull-integration-realcluster-test

[HuSharp]

/merge

[ti-chi-bot]

@HuSharp: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

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

Commit hash: 287d209

[ti-chi-bot]

@HuSharp: Your PR was out of date, I have automatically updated it for you.

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.