Fix RayCluster parser after enabling the SuperSlicing feature flag by jamOne- · Pull Request #988

Fix RayCluster parser after enabling the SuperSlicing feature flag by jamOne- · Pull Request #988 · AI-Hypercomputer/xpk

Fix RayCluster parser after enabling the SuperSlicing feature flag.

  File "/opt/hostedtoolcache/Python/3.10.19/x64/lib/python3.10/site-packages/xpk/commands/cluster.py", line 301, in _validate_num_slices_and_set_default
    if args.num_cubes is not None and not args.super_slicing:
AttributeError: 'Namespace' object has no attribute 'num_cubes'

Added a RC golden.