Fix stacktraces

[aronisstav]

Summary

The patch c95c2c6 made it possible for stacktraces to linger and be reported when they were irrelevant. This patch fixes this.

Fixes aronisstav#42.

Checklist

• Has tests (or doesn't need them)
• Updates CHANGELOG (or too minor)
• References related Issues

[codecov]

Codecov Report

Merging #276 into master will increase coverage by <.01%.
The diff coverage is 82.75%.

@@            Coverage Diff             @@
##           master     #276      +/-   ##
==========================================
+ Coverage    94.2%   94.21%   +<.01%     
==========================================
  Files          12       12              
  Lines        3575     3580       +5     
==========================================
+ Hits         3368     3373       +5     
  Misses        207      207

Flag	Coverage Δ
#tests	93.88% <82.75%> (ø)	⬆️
#tests_real	84.38% <72.41%> (-0.01%)	⬇️
#unit_tests	2.54% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
src/concuerror_callback.erl	92.61% <80%> (+0.07%)	⬆️
src/concuerror_inspect.erl	91.89% <88.88%> (-1.22%)	⬇️

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