Make pltcl regression tests safe for Danish locale.

Another peculiarity of Danish locale is that it has an unusual idea
of how to sort upper vs. lower case.  One of the pltcl test cases has
an issue with that.  Now that COLLATE works in all supported branches,
we can just change the test to be locale-independent, and get rid of
the variant expected file that used to support non-C locales.