[confighttp] Reuse zstd reader objects

[ethercrow]

Description

Allocating zstd reader objects on every incoming requests leads to a lot of byte buffers being allocated and collected. The compression library recommends reusing readers to avoid these allocations.

Link to tracking issue

Fixes #11824

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: ethercrow / name: Dmitry Ivanov (a8bbbdf, 0419397, 505ee1c, 609e89a, f3d4394)

[codecov]

Codecov Report

Attention: Patch coverage is 85.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 91.44%. Comparing base (be09659) to head (0419397).
Report is 17 commits behind head on main.

Files with missing lines	Patch %	Lines
config/confighttp/compression.go	85.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13396      +/-   ##
==========================================
- Coverage   91.48%   91.44%   -0.05%     
==========================================
  Files         529      529              
  Lines       29508    29523      +15     
==========================================
  Hits        26996    26996              
- Misses       1985     1996      +11     
- Partials      527      531       +4     

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