FiltersOpenTURNS: require OpenTURNS 1.12 or newer
The 1.12 release included a proper usgae interface that allows us to
just use the target directly. We can also drop the UseOpenTURNS
file
as its purpose is handled by the imported target.
Cc: @cory.quammen @ryan.krattiger1 @jschueller @Neumann-A
Backport: paraview/release