kivy: locale: set default language to English

This reverts 7cb11ceda4 (set default language to OS lang).
Some languages (e.g. CJK, Arabic) do not work at all with kivy due to font issues,
so we should never use those as default. It is easiest to just default to English for now.

related https://github.com/spesmilo/electrum/issues/2032
related https://github.com/spesmilo/electrum/issues/4618
related https://github.com/spesmilo/electrum/issues/7494

electrum/gui/kivy/util.py

@@ -26,7 +26,11 @@ def address_colors(wallet, addr):
 def get_default_language() -> str:
     if platform != 'android':
         return 'en_UK'
-    from jnius import autoclass
-    Locale = autoclass("java.util.Locale")
-    lang = str(Locale.getDefault().toString())
-    return lang if lang else 'en_UK'
+    # FIXME: CJK/Arabic/etc languages do not work at all with kivy due to font issues,
+    #        so it is easiest to just default to English... (see #2032)
+    return 'en_UK'
+    # # try getting the language of the Android OS
+    # from jnius import autoclass
+    # Locale = autoclass("java.util.Locale")
+    # lang = str(Locale.getDefault().toString())
+    # return lang if lang else 'en_UK'