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

idea/testData/quickfix/changeSignature/removeFunctionSecondParameter2.kt.after

@@ -0,0 +1,9 @@
+// "Remove parameter 'y'" "true"
+// DISABLE-ERRORS
+
+fun foo(x: Int) {
+    foo();
+    foo(1<caret>);
+    foo(1);
+    foo(2);
+}