Add checkpoint artifact path prefix to MLflow logger #26673

Job	Run time
build-packages / build-packages (lightning)	20s
build-packages / build-packages (fabric)	20s
build-packages / build-packages (pytorch)	24s
build-packages / merge-artifacts	7s
install-pkg (ubuntu-22.04, fabric, 3.9)	1m 41s
install-pkg (ubuntu-22.04, fabric, 3.11)	1m 47s
install-pkg (ubuntu-22.04, pytorch, 3.9)	1m 48s
install-pkg (ubuntu-22.04, pytorch, 3.11)	1m 50s
install-pkg (ubuntu-22.04, lightning, 3.9)	2m 25s
install-pkg (ubuntu-22.04, lightning, 3.11)	1m 51s
install-pkg (ubuntu-22.04, notset, 3.9)	1m 55s
install-pkg (ubuntu-22.04, notset, 3.11)	1m 53s
install-pkg (macOS-14, fabric, 3.9)	56s
install-pkg (macOS-14, fabric, 3.11)	39s
install-pkg (macOS-14, pytorch, 3.9)	1m 11s
install-pkg (macOS-14, pytorch, 3.11)	48s
install-pkg (macOS-14, lightning, 3.9)	1m 13s
install-pkg (macOS-14, lightning, 3.11)	43s
install-pkg (macOS-14, notset, 3.9)	52s
install-pkg (macOS-14, notset, 3.11)	50s
install-pkg (windows-2022, fabric, 3.9)	2m 29s
install-pkg (windows-2022, fabric, 3.11)	2m 12s
install-pkg (windows-2022, pytorch, 3.9)	2m 42s
install-pkg (windows-2022, pytorch, 3.11)	2m 8s
install-pkg (windows-2022, lightning, 3.9)	2m 11s
install-pkg (windows-2022, lightning, 3.11)	2m 23s
install-pkg (windows-2022, notset, 3.9)	2m 22s
install-pkg (windows-2022, notset, 3.11)	2m 3s
	42m 3s

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