ABC controller test

[MichaelClerx]

Fixes several oddities in ABC controller test:

• A file called "True" was being written on every run
• Logged output was not compared to expected results
• Logging tests used 1000s of iterations, making the logging test take 7 seconds on my machine
• A new ABCController was created but not used for most of the logging tests

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (86237c1) 100.00% compared to head (249f2b7) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1464   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           97        97           
  Lines         9524      9524           
=========================================
  Hits          9524      9524           

Impacted Files	Coverage Δ
pints/_abc/__init__.py	100.00% <100.00%> (ø)
pints/_abc/_abc_rejection.py	100.00% <100.00%> (ø)

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[MichaelClerx]

Anyone feel like reviewing this one? Fixes some annoyances in a test, no hard maths or anything :D @pints-team/devs ?