Remove the EXE file test spec

This thing has been a problem since forever, given cross-platform issues and random collisions with other file magic signatures.

See #3807 and #2793 and the even earlier Redmine bug.

This should not close the bug, since we're merely avoiding the random fails by not testing at all. We /should/ test, but in the meantime, we can't suffer these failures that throw me (at least) into a panic every
time.

Let's fix this, but in the meantime, stop false positiving.