intel/compiler/mesh: use slice id of task urb handles in mesh shaders

intel/compiler/mesh: use slice id of task urb handles in mesh shaders

When mesh shader is spawned on a different slice than the originating
task shader, then input task urb handle can come from a different
slice, so masking this information off will load data from the current
slice, instead of the one where real data are.

Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21007>