It had been present ever since at least 88c437c597b604524d50f450506285a594bd03a5
"moved from api" from 2000, but was apparently never implemented nor used at
least in OOo/LO itself.  It is problematic as it uses reserved identifiers
("getDisplayLanguage_Default" etc.) that contain underscores and start with a
lowercase letter, and a planned change to unoidl-write will no longer tolerate
usage of such reserved identifiers (see the TODO in
unoidl/source/sourceprovider-scanner.l).

Change-Id: I76a3a3da7b7c1f4c109ca7a12c9f07857ca1be1d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/123544
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>