Extract Function: Do not suggest "unit" as function name

#KT-6402 Fixed

idea/testData/refactoring/extractFunction/parameters/misc/multiDeclaration.kt.after

@@ -3,10 +3,10 @@
 // SIBLING:
 fun main(args: Array<String>) {
     val (a, b) = Data(1, 2)
-    unit(a)
+    __dummyTestFun__(a)
 }
 
-private fun unit(a: Int) {
+private fun __dummyTestFun__(a: Int) {
     a
 }