'end this conversation afterwards' checked by default

closes #2364 #2382

src/main/res/layout/dialog_clear_history.xml

@@ -21,6 +21,7 @@
         android:layout_width="wrap_content"
         android:textColor="?attr/color_text_primary"
         android:layout_height="wrap_content"
+        android:checked="true"
         android:text="@string/also_end_conversation" />
 
 </LinearLayout>