t/run/locale.t: Rmv test that isn't generally valid

The return from setlocale() on a new locale is documented in Linux as
opaque, even though the Linux smokers we have return the name of the
new locale.  It turns out that VMS actually does return something
different, and this test fails there.  So, the test is testing for
something that just happens to be currently true on many of our systems;
hence isn't general, and hence shouldn't be tested for.

And, the test isn't necessary, as we can infer from the other tests in
the file that a locale passed via the environment actually takes hold,
as we do so for a locale which has a comma radix, and test that the
radix is correctly set.