Set cwd in redis process

[alonre24]

Set cwd upon launching redis subprocess to be the logs dir rather than using the --dir configuration to set the current dir.
The motivation for that is when running sanitizer which instruments redis process, the sanitizer creates its log in cwd BEFORE redis initializes and sets cwd according to the --dir configuration. With this change, we can guarantee that logs will always be created in the logs path.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (55f3ff0) 32.41% compared to head (0d96398) 32.36%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #219      +/-   ##
==========================================
- Coverage   32.41%   32.36%   -0.06%     
==========================================
  Files          17       17              
  Lines        2588     2586       -2     
==========================================
- Hits          839      837       -2     
  Misses       1749     1749              

Flag	Coverage Δ
unittests	32.36% <100.00%> (-0.06%)	⬇️

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