Fix up matmul.short.mtmul_user_program_config_mcast_1d sweep generation

[bbradelTT]

The following commit broke the generation for matmul.short.matmul_user_program_config_mcast_1d because the function ttnn.num_cores_to_corerange_set returns std::set instead of CoreRangeSet now.
https://github.com/tenstorrent/tt-metal/commit/014940bada16287f339a9a38a7e271c18e84a2b3#diff-7bc2990a155620f65e77ff7[…]c3503078255aeb1d0f0b9966e0450

There was a comment on the old function that says TODO: Switch num_cores_to_corerange_set to always return CoreRangeSet but that didn't happen.

For now update the generation to use the returned set to create a CoreRangeSet.