Work around unintentionally translated String resource crashing SystemUI.

A resource file name donottranslate.xml stops the Android Studio linter
complaining about untranslated string resources, but this is inconsistent
with current aapt behavior because aapt doesn't implicitly infer
translatable="false" for such strings. Therefore, pseudo translations
are generated for pseudo locales such as en-XA, even though that was
not intended.

This looks to be a bug in aapt. As a short-term workaround to
stop SystemUI crashing, this CL explicitly marks the offending
Strings as translatable="false", which should stop them being
translated into pseudo locales and therefore stop SystemUI crashing.

Bug: 126423638
Test: Treehugger
Change-Id: Ice903070ea89dbef17b347c5e0ccd6a8d896e432