[COREV] Re-enable Windows testing
Created by: simonpcook
The commit that added CI for the COREV LLVM fork disabled Windows testing due to timeouts, but this looks to be just a case of cold build caches, and really could occur wiht any of the tests. This re-enables the Windows tests, and explains the situation of what to do should the tests be cancelled due to hitting the 360-minute limit.
(Should the action fail, I think it used to be possible to manually retrigger a test)