Refs #9902. Speeding up InvertMDDimTest

The was using a large MDHistoWorkspace, shrinking it by a factor of 10 in each dimension made the test faster without changing what the test was doing.
Refs #9902. Speeding up ProjectMDTest

The same procedure as for InvertMDDimTest - shrinking the example data without changing what the test does.
Merge remote-tracking branch 'origin/feature/9902_slow_unit_tests'