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

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

@@ -0,0 +1,19 @@
+// "Remove parameter 'i'" "true"
+trait Z {
+    fun f()
+}
+
+trait ZZ {
+    fun f()
+}
+
+trait ZZZ: Z, ZZ {
+}
+
+trait ZZZZ : ZZZ {
+    override fun f()
+}
+
+fun usage(z: ZZZ) {
+    z.f()
+}