Remove OI/NI attributes from test data

compiler/testData/diagnostics/tests/smartCasts/elvis/impossible.kt

@@ -17,7 +17,7 @@ fun foo(list: StringList, arg: Unstable) {
     list.remove(arg.first)
     if (arg.first?.isEmpty() ?: false) {
         // Should be still resolved to extension, without smart cast or smart cast impossible
-        list.remove(<!SMARTCAST_IMPOSSIBLE{OI}!>arg.first<!>)
+        list.remove(arg.first)
     }
 }
 
@@ -35,6 +35,6 @@ fun bar(list: BooleanList, arg: UnstableBoolean) {
     list.remove(arg.first)
     if (arg.first ?: false) {
         // Should be still resolved to extension, without smart cast or smart cast impossible
-        list.remove(<!SMARTCAST_IMPOSSIBLE{OI}!>arg.first<!>)
+        list.remove(arg.first)
     }
 }