fix: delete null value in request body

[Baoyuantop]

Please answer these questions before submitting a pull request, or your PR will get closed.

Why submit this pull request?

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

What changes will this PR take into?

In the optional InputNumber component of the entire project, when the user chooses not to fill in, the value of the field in the request body is null, which will cause a request error.

The correct approach is to delete all fields with null values in the request body.

Related issues

fix #2019

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

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[codecov-commenter]

Codecov Report

Merging #2042 (f6a67e1) into master (af85591) will increase coverage by 1.82%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2042      +/-   ##
==========================================
+ Coverage   63.52%   65.35%   +1.82%     
==========================================
  Files         121      121              
  Lines        3213     3221       +8     
  Branches      779      782       +3     
==========================================
+ Hits         2041     2105      +64     
+ Misses       1172     1116      -56     

Flag	Coverage Δ
frontend-e2e-test	65.35% <100.00%> (+1.82%)	⬆️

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

Impacted Files	Coverage Δ
web/src/app.tsx	100.00% <100.00%> (ø)
web/src/helpers.tsx	72.13% <0.00%> (+3.27%)	⬆️
web/src/components/Upstream/UpstreamForm.tsx	92.20% <0.00%> (+9.09%)	⬆️
...ts/Upstream/components/active-check/ReqHeaders.tsx	50.00% <0.00%> (+41.66%)	⬆️
...m/components/active-check/Healthy/HttpStatuses.tsx	75.00% <0.00%> (+66.66%)	⬆️
...components/active-check/Unhealthy/HttpStatuses.tsx	75.00% <0.00%> (+66.66%)	⬆️
...mponents/Upstream/components/active-check/Host.tsx	100.00% <0.00%> (+66.66%)	⬆️
...mponents/Upstream/components/active-check/Port.tsx	100.00% <0.00%> (+66.66%)	⬆️
...mponents/Upstream/components/active-check/Type.tsx	100.00% <0.00%> (+66.66%)	⬆️
...nents/Upstream/components/active-check/Timeout.tsx	100.00% <0.00%> (+66.66%)	⬆️
... and 8 more

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[liuxiran]

merged, thanks a lot