[FIR] Remove the fast path if as insignificant

This if is a bit inconsistent with the
LUB checking approach, so if it doesn't
improve performance it's better to remove it.

compiler/fir/analysis-tests/testData/resolveWithStdlib/intellij/IntersectionWithJavaString.kt

@@ -5,5 +5,5 @@
 
 fun collapse(path: String) {
     val result = (path as <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.String<!>).replace("123", "456")
-    if (<!EQUALITY_NOT_APPLICABLE_WARNING!>result !== path<!>) {}
+    if (result !== path) {}
 }