Add formatting to Union_master comp #3534

Job	Run time
ubuntu-24.04.gcc-13.openmpi.python-3.12	12m 56s
windows-11-arm.cl.exe.msmpi.python-3.13	9m 50s
ubuntu-24.04.clang.openmpi.python-3.12	14m 29s
windows-latest.gcc.exe.msmpi.python-3.13	16m 34s
	53m 49s

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