Bug 1655859 - Unship ::-moz-focus-outer in all channels. r=boris

It was disabled on nightly in bug 1636998. It does nothing anymore.

There's no regression known and I'm hoping we can get rid of it.

Differential Revision: https://phabricator.services.mozilla.com/D85208

modules/libpref/init/StaticPrefList.yaml

@@ -5967,7 +5967,7 @@
 # Whether the ::-moz-focus-outer pseudo-class is parsed.
 - name: layout.css.moz-focus-outer.enabled
   type: RelaxedAtomicBool
-  value: @IS_NOT_NIGHTLY_BUILD@
+  value: false
   mirror: always
   rust: true