how to distinguish spack tests in validation_tests directory

[shahzebsiddiqui]

@wspear

The validation_tests directory contains a lot of tests and it is not clear which ones invoke spack test and which one are not. It would be better to either remove all test that invoke spack test from this repo, if there is a need to keep them around i would suggest put them in a separate directory so its easier to keep track of them.

One option would be to have two top-level directories validation_tests and spack_tests. I suspect there will be translation as test migrates from validation_tests --> spack_tests when a package supports spack test. It is something to consider, i am trying to distinguish which tests should run from E4S Testsuite and which ones run from spack test and i dont want to write redundant tests from two different test suites.