remove optimization which causes inaccurate results

[ashtul]

Remove usage of optimization which resulted in false results.
Can't find the original algorithm to try and fix.
Should the code of optimization be removed altogether?

[codecov]

Codecov Report

Merging #1052 into master will decrease coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1052      +/-   ##
==========================================
- Coverage   83.14%   83.12%   -0.03%     
==========================================
  Files         144      144              
  Lines       18626    18626              
==========================================
- Hits        15487    15482       -5     
- Misses       3139     3144       +5

Impacted Files	Coverage Δ
src/aggregate/reducers/quantile.c	63.46% <100%> (ø)	⬆️
src/legacy_gc.c	85.16% <0%> (-3.82%)	⬇️
src/indexer.c	92.88% <0%> (+0.33%)	⬆️
src/util/quantile.c	94% <0%> (+2%)	⬆️

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