Use new feature gate in impl-trait tests

Author: ecstatic-morse

src/test/ui/type-alias-impl-trait/issue-53096.rs

@@ -1,5 +1,5 @@
 // check-pass
-#![feature(const_fn, const_fn_fn_ptr_basics)]
+#![feature(const_fn_impl_trait, const_fn_fn_ptr_basics)]
 #![feature(type_alias_impl_trait)]
 
 type Foo = impl Fn() -> usize;

src/test/ui/type-alias-impl-trait/issue-53678-generator-and-const-fn.rs

@@ -1,6 +1,6 @@
 // check-pass
 
-#![feature(const_fn, generators, generator_trait, type_alias_impl_trait)]
+#![feature(const_fn_impl_trait, generators, generator_trait, type_alias_impl_trait)]
 
 use std::ops::Generator;
 

src/test/ui/type-alias-impl-trait/structural-match-no-leak.rs

@@ -1,4 +1,4 @@
-#![feature(const_fn, type_alias_impl_trait)]
+#![feature(const_fn_impl_trait, type_alias_impl_trait)]
 
 type Bar = impl Send;
 

src/test/ui/type-alias-impl-trait/structural-match.rs

@@ -1,4 +1,4 @@
-#![feature(const_fn, type_alias_impl_trait)]
+#![feature(const_fn_impl_trait, type_alias_impl_trait)]
 
 type Foo = impl Send;