remove context sync.Pool to avoid data races.

[lyouthzzz]

Description (what this PR does / why we need it):

This PR will fix data race issues caused by object reuse with sync.Pool.

Which issue(s) this PR fixes (resolves / be part of):

more detail for bug issue: #3070

Other special notes for the reviewers:

[codecov-commenter]

Codecov Report

Merging #3072 (6d36bc8) into main (3fc8fb7) will decrease coverage by 0.12%.
The diff coverage is 100.00%.

❗ Current head 6d36bc8 differs from pull request most recent head 52aecce. Consider uploading reports for the commit 52aecce to get more accurate results

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@@            Coverage Diff             @@
##             main    #3072      +/-   ##
==========================================
- Coverage   84.46%   84.35%   -0.12%     
==========================================
  Files          88       88              
  Lines        3992     3988       -4     
==========================================
- Hits         3372     3364       -8     
- Misses        446      448       +2     
- Partials      174      176       +2     

Files	Coverage Δ
transport/http/router.go	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes