fix: remove counter to keep aligned with early return in fast path

[CrystalAnalyst]

Please briefly answer these questions:

• what problem are you trying to solve? (or if there's no problem, what's the motivation for this change?)
  Update testing logic to keep aligned with early return in fast path.
  Since we can return early in fast path when the number of conlicts is so large that we cannot reach SuperQuorum.
  So we DO NOT NEED to force all the 5 servers to handle the propose.
  related issue : [Bug]: test_unary_propose_fast_path_fallback_slow_path will randomly failed  #840

• what changes does this pull request make?
  Remove the counter, and the rest part works fine (Successfully fallback to slow path) .

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.72%. Comparing base (e35b35a) to head (97aa29d).
Report is 121 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #859      +/-   ##
==========================================
+ Coverage   75.55%   75.72%   +0.16%     
==========================================
  Files         180      187       +7     
  Lines       26938    27822     +884     
  Branches    26938    27822     +884     
==========================================
+ Hits        20353    21067     +714     
- Misses       5366     5465      +99     
- Partials     1219     1290      +71     

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[Phoenix500526]

LGTM