Fix tests: "infix modifier required" and "operator modifier required" errors

idea/testData/intentions/infixCallToOrdinary/simpleInfixFunctionCall.kt

@@ -1,3 +1,5 @@
+infix fun Int.compareTo(other: Int) = 0
+
 fun foo(x: Int) {
     x <caret>compareTo 1
 }