Revert test case added by commit
1e165d05fe06a9072867607886f818bc255507db.
The buildfarm is still showing at least three distinct behaviors for
a bad locale name in CREATE COLLATION. Although this test was helpful
for getting the error reporting code into some usable shape, it doesn't
seem worth carrying multiple expected-files in order to support the
test in perpetuity. So pull it back out.
Discussion: https://postgr.es/m/CAKKotZS-wcDcofXDCH=sidiuajE+nqHn2CGjLLX78anyDmi3gQ@mail.gmail.com