GDI+ stability fixes for the benchmark and tests

[Lakritzator]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

Some changes to make the usages of GDI in benchmarks and tests more stable, this should hopefully prevent "a generic error occurred in GDI+". Hopefully I didn't miss one...

If you new Pen, Brush or Fonts, these need to be disposed.

[CLAassistant]

All committers have signed the CLA.

[JimBobSquarePants]

@Lakritzator Ah this is great! 👍

[codecov]

Codecov Report

Merging #835 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #835      +/-   ##
==========================================
+ Coverage   88.84%   88.84%   +<.01%     
==========================================
  Files        1015     1015              
  Lines       44167    44169       +2     
  Branches     3181     3181              
==========================================
+ Hits        39241    39243       +2     
  Misses       4201     4201              
  Partials      725      725

Impacted Files	Coverage Δ
...stUtilities/ReferenceCodecs/SystemDrawingBridge.cs	88.73% <100%> (+0.32%)	⬆️

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[Lakritzator]

I'm not sure how reproducible the problems were, but I guess I didn't make it worse. Just let me know when you see the issue again, and I will have a more thorough look! But my gut feeling tells me I got all...

[Lakritzator]

P.S. I like the automation you did, I really should use this CLAassistant too...