Remove 'static bound in assoc const test.

Types do not have to be `'static` to be referenced in
associated consts.

Author: withoutboats

src/test/run-pass/associated-const-outer-ty-refs.rs

@@ -13,8 +13,7 @@ trait Lattice {
     const BOTTOM: Self;
 }
 
-// FIXME(#33573): this should work without the 'static lifetime bound.
-impl<T: 'static> Lattice for Option<T> {
+impl<T> Lattice for Option<T> {
     const BOTTOM: Option<T> = None;
 }