Remove testing headers from benchmarking

The code in `vtkm/cont/Testing.h` now requires a library, which is not
built if testing is not built. Thus, the benchmarking code was giving a
compile error if benchmarking was on but testing was off.

Change the benchmarking to not rely on anything in the Testing
framework. This means using classes in `vtkm/source` instead of
`MakeTestData`. Also avoid using the `TestValue` defined for the tests.
(In one case, we have a simple replacement.) Also had to fix a problem
with a header file not defining everything it needed to compile.
5 jobs for benchmark-does-not-need-testing