Changes

[mlir] Enable MLIRDialectUtilsTests

Also remove `TooFewDims` test which tried to create an invalid AffineMap.
The creation of an invalid AffineMap is rejected by `willBeValidAffineMap`,
as a result we can deprecate the test.

Reviewed By: bondhugula

Differential Revision: https://reviews.llvm.org/D114657