[Polly] Update isl to isl-0.23-61-g24e8cd12.

This fixes llvm.org/PR48554

Some test cases had to be updated because the hash function for
union_maps have been changed which affects the output order.

GitOrigin-RevId: 842314b5f078b5c63df1d7e271fc6fad8461d44f
137 files changed