tests: use python3 to run http_api test to fix failed integration_tests (#5473)

[ti-chi-bot]

This is an automated cherry-pick of #5473

What problem does this PR solve?

Issue Number: close #5474

What is changed and how it works?

Our CI envs still default to python2 to run tests. http_api requires using requests which brings certifi. Actually certifi's recent releases doesn't support python2 any more.

Release note

None

[ti-chi-bot]

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[zhangyangyu]

/run-all-tests

[zhangyangyu]

/run-all-tests

[zhangyangyu]

/run-kafka-integration-test

[zhangyangyu]

/run-verify

[zhangyangyu]

/run-verify

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-6.0@2f363f6). Click here to learn what that means.
The diff coverage is n/a.

Flag	Coverage Δ
cdc	60.9495% <0.0000%> (?)
dm	51.8829% <0.0000%> (?)

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

@@               Coverage Diff                @@
##             release-6.0      #5479   +/-   ##
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  Coverage               ?   55.9046%           
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  Files                  ?        524           
  Lines                  ?      66905           
  Branches               ?          0           
================================================
  Hits                   ?      37403           
  Misses                 ?      25827           
  Partials               ?       3675           

[Rustin170506]

/merge

[ti-chi-bot]

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

Commit hash: 9c023ad

[VelocityLight]

This pull request is closed because it's related version has closed automatic cherry-picking.
If it's still needed, you can reopen it or just regenerate it using bot,
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