Big change in quickfix tests: no stupid test data format with "before" and "after" file prefixes

idea/testData/quickfix/changeSignature/removeConstructorParameter.kt.after

@@ -0,0 +1,12 @@
+// "Remove parameter 'x'" "true"
+// DISABLE-ERRORS
+
+open class Base() {
+    val y = Base();
+
+    fun f() {
+        val base = Base();
+    }
+}
+
+open class Inherited(x: Int) : Base() {}