Fix rustdoc UI tests

Also removed a test that was literally a duplicate of the one I kept.

Author: camelid

tests/rustdoc-ui/associated-constant-not-allowed-102467.rs

@@ -1,7 +1,8 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/102467>.
 // It ensures that the expected error is displayed.
 
-#![feature(associated_const_equality)]
+#![expect(incomplete_features)]
+#![feature(associated_const_equality, min_generic_const_args)]
 
 trait T {
     type A: S<C<X = 0i32> = 34>;
@@ -10,6 +11,7 @@ trait T {
 }
 
 trait S {
+    #[type_const]
     const C: i32;
 }
 

tests/rustdoc-ui/associated-constant-not-allowed-102467.stderr

@@ -1,5 +1,5 @@
 error[E0229]: associated item constraints are not allowed here
-  --> $DIR/associated-constant-not-allowed-102467.rs:7:17
+  --> $DIR/associated-constant-not-allowed-102467.rs:8:17
    |
 LL |     type A: S<C<X = 0i32> = 34>;
    |                 ^^^^^^^^ associated item constraint not allowed here
@@ -11,7 +11,7 @@ LL +     type A: S<C = 34>;
    |
 
 error[E0229]: associated item constraints are not allowed here
-  --> $DIR/associated-constant-not-allowed-102467.rs:7:17
+  --> $DIR/associated-constant-not-allowed-102467.rs:8:17
    |
 LL |     type A: S<C<X = 0i32> = 34>;
    |                 ^^^^^^^^ associated item constraint not allowed here