[tests] Remove not-identical expectation for Type values

The instantiation at runtime implies non-constant type expressions
but canonicalization is unspecified so backends should be allowed
to optimize by canonicalizing types.

Change-Id: I2f1cab6ac68a1ce156b15af0b99e02d03b7b3dca
Issue: https://github.com/dart-lang/sdk/issues/46837
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/209663
Commit-Queue: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>

tests/language/type_object/explicit_instantiated_type_literal_test.dart

@@ -45,9 +45,7 @@ void main() {
   Expect.identical(C<int>, prefix.C<int>);
 
   (<T extends num>() {
-    Expect.notIdentical(C<T>, C<T>);
     Expect.equals(C<T>, C<T>);
-    Expect.notIdentical(prefix.C<T>, prefix.C<T>);
     Expect.equals(prefix.C<T>, prefix.C<T>);
   }<int>());
 }