Refactor to use ParallelTestRunner in the tests

[odow]

No description provided.

[odow]

We'd need to drop pre 1.10 support. But that could be okay. We've done it with MOI and many others.

[odow]

If this looks good I'll split baaf401 into a separate PR.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.37%. Comparing base (e012c26) to head (dea5388).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Containers/DenseAxisArray.jl	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4119      +/-   ##
==========================================
- Coverage   99.81%   98.37%   -1.44%     
==========================================
  Files          43       43              
  Lines        5927     5854      -73     
==========================================
- Hits         5916     5759     -157     
- Misses         11       95      +84     

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[odow]

I'll do #4121 separately