refactor(redis): rename tx to pipeliner

[alextes]

"transaction" is exactly what we shouldn't call the pipeliner. Redis offers both, the latter differs precisely in that it is not atomic.

• make lint. (a lot of depguard errors, but not related to these changes.)
• make test-race
• go mod tidy
• I have seen and agree to CONTRIBUTING.md

[codecov-commenter]

Codecov Report

Merging #499 (4d54559) into main (753275c) will increase coverage by 0.81%.
Report is 6 commits behind head on main.
The diff coverage is 91.83%.

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@@            Coverage Diff             @@
##             main     #499      +/-   ##
==========================================
+ Coverage   30.58%   31.40%   +0.81%     
==========================================
  Files          24       24              
  Lines        4783     4853      +70     
==========================================
+ Hits         1463     1524      +61     
- Misses       3121     3136      +15     
+ Partials      199      193       -6     

Flag	Coverage Δ
unittests	31.40% <91.83%> (+0.81%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
datastore/redis.go	60.20% <91.30%> (ø)
datastore/utils.go	80.00% <100.00%> (ø)

... and 6 files with indirect coverage changes