fix: Clean includes in `Geant4Manager` #21562

Job	Run time
linux_ubuntu	5m 36s
macos	5m 22s
linux_ubuntu_extra (ubuntu2404, 17)	6m 51s
linux_ubuntu_extra (ubuntu2204_cpp20, 20)	6m 32s
linux_ubuntu_extra (ubuntu2204_clang, 17)	5m 51s
linux_physmon	26m 47s
linux_examples_test	38m 51s
linux_physmon_perf_report	0s
	1h 35m 50s

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