WaveToyX: adapt to CarpetX implementation change #1312

Job	Run time
download-build-test (cpu, real32, debug)	11m 24s
download-build-test (cpu, real64, debug)	11m 44s
download-build-test (cpu, real64, optimize)	16m 47s
download-build-test (cuda, real32, debug)	23m 27s
download-build-test (cuda, real64, debug)	24m 24s
download-build-test (cuda, real64, optimize)	23m 38s
download-build-test (rocm, real64, optimize)	19m 42s
download-build-test (oneapi, real64, optimize)	29m 55s
	2h 41m 1s

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