LWG-3553 Useless constraint in `split_view::outer-iterator::value_type::begin()` (#1990)

stl/inc/ranges

@@ -3321,16 +3321,10 @@ namespace ranges {
                     is_nothrow_move_constructible_v<_Outer_iter>) // strengthened
                     : _First{_STD move(_First_)} {}
 
-                _NODISCARD constexpr auto begin() const requires copyable<_Outer_iter> {
+                _NODISCARD constexpr auto begin() const {
                     return _Inner_iter<_Const>{_First};
                 }
 
-                // clang-format off
-                _NODISCARD constexpr auto begin() requires (!copyable<_Outer_iter>) {
-                    return _Inner_iter<_Const>{_STD move(_First)};
-                }
-                // clang-format on
-
                 _NODISCARD constexpr default_sentinel_t end() const noexcept {
                     return default_sentinel;
                 }