Dropped redundant code which was required for lambda signature completion when the syntax was different

#KT-12033 Fixed

idea/idea-completion/testData/basic/common/KT12033.kt

@@ -0,0 +1,8 @@
+fun main(foo: Foo) {
+    foo.apply {
+        is<caret>
+    }
+}
+class Foo(val isValid: String)
+
+// EXIST: isValid