patch 9.1.2119: tests: Test_language_cmd fails on OpenBSD

patch 9.1.2119: tests: Test_language_cmd fails on OpenBSD

Problem:  tests: Test_language_cmd fails on OpenBSD because the test
          uses an invalid locale name and expects the command to produce
          an error. OpenBSD accepts (almost) any locale name as valid by
          design, so the :lang command succeeds and the test fails.
Solution: Slightly update the "bad" locale name to make it something
          that OpenBSD considers invalid by adding a dot (but not ending
          with ".UTF-8"). Maintain the original two underscores in the
          name because that ensures Windows will also see it as invalid
          (Kevin Goodsell).

closes: #19280

Signed-off-by: Kevin Goodsell <kevin-opensource@omegacrash.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>