Fix and simplify continuous integration

[jcfr]

As of August 13th 2021, all jobs are failing:

Source: https://app.circleci.com/pipelines/github/Slicer/SlicerExecutionModel/19/workflows/ed1fad58-f7e9-4df7-8887-ddf82dd7e454

Suggested plan:

• Remove these obsolete jobs:

  SlicerExecutionModel/.circleci/config.yml

  Lines 56 to 58 in f19d6e8

  	- itk-v4.8.0_use_system_libraries-off
  	- itk-v4.10.1_use_system_libraries-off
  	- itk-v4.13.0_use_system_libraries-off

• Update itk-master_use_system_libraries-off docker image

• Add itk-v5.1.2_use_system_libraries-off and itk-v5.2.1_use_system_libraries-off

For more details:

• https://github.com/Slicer/SlicerExecutionModel#adding-or-updating-a-testing-environment
• https://github.com/Slicer/SlicerExecutionModel/tree/master/test

[hjmjohnson]

Is this still outstanding?

[jcfr]

Is this still outstanding?

Indeed, it needed to be address. This ended up being more time consuming than anticipated.