For #28298: Disable deletion of last element in search engines list

When removing search engines from settings,
the option to delete the last one should not be
available

app/src/main/java/org/mozilla/fenix/settings/search/RadioSearchEngineListPreference.kt

@@ -83,7 +83,7 @@ class RadioSearchEngineListPreference @JvmOverloads constructor(
                 engine = engine,
                 layoutInflater = layoutInflater,
                 res = context.resources,
-                allowDeletion = state.searchEngines.size > 1,
+                allowDeletion = state.searchEngines.count { it.type != SearchEngine.Type.APPLICATION } > 1,
                 isSelected = engine == state.selectedOrDefaultSearchEngine,
             )