remove experimental from coordination API

[qrort]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Coordination API is experimental

What is the new behavior?

Mark API as stable

[github-actions]

summary

Base version: v3.108.3 (master)
Suggested version: v3.108.4

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.07%. Comparing base (26a84de) to head (cc86fe0).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1794      +/-   ##
==========================================
- Coverage   71.19%   71.07%   -0.12%     
==========================================
  Files         382      382              
  Lines       39145    39145              
==========================================
- Hits        27868    27823      -45     
- Misses      10149    10189      +40     
- Partials     1128     1133       +5     

Flag	Coverage Δ
experiment	70.64% <ø> (-0.11%)	⬇️
go-1.21.x	69.26% <ø> (-0.11%)	⬇️
go-1.24.x	71.06% <ø> (-0.12%)	⬇️
integration	53.90% <ø> (-0.17%)	⬇️
macOS	40.51% <ø> (-0.04%)	⬇️
ubuntu	71.07% <ø> (-0.13%)	⬇️
unit	40.54% <ø> (-0.01%)	⬇️
windows	40.53% <ø> (-0.02%)	⬇️
ydb-24.1	51.24% <ø> (-0.36%)	⬇️
ydb-24.2	51.76% <ø> (-0.11%)	⬇️
ydb-24.3	52.20% <ø> (-0.20%)	⬇️
ydb-24.4	51.76% <ø> (-0.31%)	⬇️
ydb-25.1	53.42% <ø> (-0.22%)	⬇️
ydb-nightly	70.64% <ø> (-0.11%)	⬇️

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