tests: run vfmt over some of the tests in vlib/v/tests (#9455)

vlib/v/tests/methods_on_interfaces_test.v

@@ -7,11 +7,11 @@ interface Animal {
 }
 
 fn (a Animal) info() string {
-	return "I'm a ${a.breed} ${typeof(a).name}"
+	return "I'm a $a.breed ${typeof(a).name}"
 }
 
 fn new_animal(breed string) Animal {
-	return &Cat{ breed }
+	return &Cat{breed}
 }
 
 fn test_methods_on_interfaces() {