Refs #7202. Cleaning up SaveMDTest files.
Refs #7202. Cleaning up LoadMDTest files.
Refs #7202. Adding a helper function.
Refs #7202. Cleaning up MinusMDTest files.
Refs #7202. Cleaning up CloneMDWorkspaceTest files.
Refs #7202. Cleaning up TransformMDTest files.
Refs #7202. Cleaning up SliceMDTest files.
Merge branch 'bugfix/7202_mdalg_test_file_cleanup' into develop