chore: use httptest.NewRequest instead of http.Request as incoming server request in test case

[ronething]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches

What this PR does / why we need it:

use httptest.NewRequest instead of http.Request as incoming server request.

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[codecov-commenter]

Codecov Report

Merging #1498 (e77baf4) into master (7511166) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1498   +/-   ##
=======================================
  Coverage   41.26%   41.26%           
=======================================
  Files          83       83           
  Lines        7365     7365           
=======================================
  Hits         3039     3039           
  Misses       3972     3972           
  Partials      354      354           

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