tu: Remove MSAA draw state

tu: Remove MSAA draw state

We only need to emit MSAA state once per subpass at most, unless the
pipeline switches primitive types or for framebuffer-less subpasses
(which always use sysmem anyway). Therefore it seems like draw state
skipping isn't going to bring much benefit here, and having it as a draw
state in the first place is a remnant of how this used to be part of the
pipeline state.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25076>