grub: Clear eMMC partition table on ThinkEdge SE70 #1843

Job	Run time
packages (arm64-secure, arm64)	11m 50s
packages (ubuntu-20.04, amd64)	11m 7s
packages (ubuntu-latest, riscv64)	42m 32s
manifest	3m 48s
verification (arm64, kvm)	7m 32s
verification (arm64, xen)	11m 2s
eve (arm64, kvm)	36m 18s
verification (amd64, kvm)	12m 9s
eve (arm64, xen)	35m 37s
verification (amd64, xen)	12m 45s
eve (amd64, kvm)	38m 46s
eve (amd64, xen)	25m 20s
eve (riscv64, mini)	5m 30s
trigger_assets	0s
	4h 14m 16s

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