metadata: Remove metedata without a short_description

It is mandatory for Google Play.

metadata/android/fa-IR/title.txt

@@ -1 +0,0 @@
-صفحه کلید غیرمنتظره

metadata/android/zh-CN/title.txt

@@ -1 +0,0 @@
-Unexpected Keyboard

sync_translations.py

@@ -60,6 +60,8 @@ def sync(baseline, strings):
             for key, base_string in baseline.items() ]
 
 def sync_metadata(value_dir, strings):
+    if "short_description" not in strings:
+        return # Short description is mandatory, do nothing without it.
     locale = os.path.basename(value_dir).removeprefix("values-")
     if not locale in VALUE_DIR_TO_METADATA:
         raise Exception("Locale '%s' not known, please add it into sync_translations.py" % locale)