[NI] Don't stop on a candidate with unstable smartcast error

#KT-36847 Fixed

compiler/testData/diagnostics/tests/resolve/kt36264.kt

@@ -12,7 +12,7 @@ class Cls {
 
     fun test(s: String) {
         if (s.ext is B)
-            take(<!NI;SMARTCAST_IMPOSSIBLE, SMARTCAST_IMPOSSIBLE!>s.ext<!>)
+            take(<!OI;SMARTCAST_IMPOSSIBLE!>s.ext<!>)
     }
 }
 

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

@@ -18,7 +18,7 @@ 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(<!NI;SMARTCAST_IMPOSSIBLE, SMARTCAST_IMPOSSIBLE!>arg.first<!>)
+        list.remove(<!OI;SMARTCAST_IMPOSSIBLE!>arg.first<!>)
     }
 }
 
@@ -36,6 +36,6 @@ 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(<!NI;SMARTCAST_IMPOSSIBLE, SMARTCAST_IMPOSSIBLE!>arg.first<!>)
+        list.remove(<!OI;SMARTCAST_IMPOSSIBLE!>arg.first<!>)
     }
 }

compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt

@@ -9,5 +9,5 @@ fun main() {
     var y: Number? = null
     y = 2
     { y = 1 }
-    Test.foo(<!SMARTCAST_IMPOSSIBLE, SMARTCAST_IMPOSSIBLE!>y<!>)
+    Test.foo(y)
 }