[BUG] json_matrix_test.py::test_scan_json_string fails on Spark 4

[mythrocks]

json_matrix_test.py::test_scan_json_string fails on Spark 4 because of whitespaces:

../../../../integration_tests/src/main/python/json_matrix_test.py::test_scan_json_strings[read_json_df-int_struct_formatted.json][DATAGEN_SEED=1720459618, TZ=UTC] FAILED [ 92%]
...
cpu = '{"A": 0, "B": 1}', gpu = '{"A":0,"B":1}'

We need a way for the tests to compare strings extracted from JSON inputs in a manner that isn't susceptible to immaterial whitespace differences. (Note that the whitespace differences are in neither the keys nor values, but in between.)

This test will be xfailed for the moment, as part of #11029.