Fix up some trivial test changes

Author: oli-obk

src/test/ui/rfc-2632-const-trait-impl/attr-misuse.rs

@@ -8,3 +8,4 @@ trait A {
 
 #[const_trait] //~ ERROR attribute should be applied
 fn main() {}
+//~^ ERROR `main` function is not allowed to have generic parameters

src/test/ui/unsized/issue-30355.rs

@@ -4,7 +4,6 @@ pub static Y: &'static X = {
     const Y: &'static [u8] = b"";
     &X(*Y)
     //~^ ERROR E0277
-    //~| ERROR E0277
 };
 
 fn main() {}