PTX: Remove internal instructions (#3583)

* barrier.cluster.aligned: Remove
This is not supposed to be exposed in CCCL.

* elect.sync: Remove
Not ready for inclusion yet. This needs to handle the optional extra
output mask as well.

* mapa: Remove
This has compiler bugs. We should use intrinsics instead.

Co-authored-by: Allard Hendriksen <ahendriksen@nvidia.com>

Author: bernhardmgruber