[configmiddleware] Stabilize module

[mx-psi]

Description

Stabilizes configmiddleware module.

Link to tracking issue

Fixes #13422

[mx-psi]

cc @open-telemetry/collector-approvers I will wait for at least one week and two approvals on this PR before merging

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.40%. Comparing base (4b44b64) to head (a7a10a6).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13720      +/-   ##
==========================================
- Coverage   91.42%   91.40%   -0.02%     
==========================================
  Files         641      641              
  Lines       42615    42615              
==========================================
- Hits        38959    38951       -8     
- Misses       2836     2842       +6     
- Partials      820      822       +2     

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