vulkan: Unconditionally add barriers for missing external subpass deps

vulkan: Unconditionally add barriers for missing external subpass deps

This is a very scorched-earth approach which doesn't take into account
whether or not there are any explicitly provided dependencies.  We could
take a finer-grained approach in theory but it's unlikely to matter in
practice since you usually stall in Begin/EndRenderPass anyway.

Fixes: 1d726940d288 ("vulkan: Add a common CmdBegin/EndRederPass implementation")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6203
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/7650
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19599>