[API CHANGE] Remove unused css.resource.XLocale

It had been present ever since at least 88c437c597
"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>

udkapi/com/sun/star/lang/Locale.idl

@@ -33,16 +33,6 @@ module com {  module sun {  module star {  module lang {
     displaying a number is a locale-sensitive operation; the number
     should be formatted according to the customs/conventions of the
     user's native country, region, or culture.  </p>
-
-    <p> Because a <code>Locale</code> object is just an identifier for a
-    region, no validity check is performed.  If you want to see whether
-    particular resources are available for the <code>Locale</code>, use
-    the com::sun::star::resource::XLocale::getAvailableLocales() method to ask for the
-    locales it supports.</p>
-
-    <p> Each implementation that performs locale-sensitive operations
-    allows you to get all the available objects of that type. Use the
-    com::sun::star::resource::XLocale interface to set the locale. </p>
  */
 published struct Locale
 {