fix: Call onFinishEditing_ for fields on mobile. (#7483)

On the desktop, widgetDispose_ will call onFinishEditing_ on close.

This was missing in the mobile counterpart, so any cleanups in onFinishEditing_ would not be called.

Also update the message string comment while we are touching this code.

core/field_input.ts

@@ -342,6 +342,7 @@ export abstract class FieldInput<T extends InputTypes> extends Field<
         if (text !== null) {
           this.setValue(this.getValueFromEditorText_(text));
         }
+        this.onFinishEditing_(this.value_);
       },
     );
   }