v3dv: drop blit path for depth/stencil formats

v3dv: drop blit path for depth/stencil formats

We can now implement all depth/stencil blits as compatible color blits,
so let's just have the blit shader interface simply convert any blit with
a depth/stencil format to a compatible color blit (like we were already
doing for s8d24) and get rid of the depth blitting path. This also allows
us to ignore the blit aspect in the blit pipeline cache key.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>