shared/cliconfig: Ensure client certificate key is 0600 #1451

Job	Run time
Code	6m 50s
System (1.21.x, cluster, dir)	11m 24s
System (1.21.x, cluster, btrfs)	11m 27s
System (1.21.x, cluster, lvm)	13m 4s
Client (1.21.x, ubuntu-latest)	26s
Documentation	6m 26s
System (1.21.x, cluster, zfs)	11m 51s
Client (1.21.x, macos-latest)	1m 7s
System (1.21.x, cluster, ceph)	15m 34s
Client (1.21.x, windows-latest)	2m 52s
System (1.21.x, cluster, random)	12m 22s
System (1.21.x, standalone, dir)	22m 24s
System (1.21.x, standalone, btrfs)	21m 37s
System (1.21.x, standalone, lvm)	39m 9s
System (1.21.x, standalone, zfs)	38m 27s
System (1.21.x, standalone, ceph)	1h 13m 20s
System (1.21.x, standalone, random)	22m 8s
System (stable, cluster, dir)	11m 36s
System (stable, standalone, dir)	22m 2s
System (tip, cluster, dir)	11m 29s
System (tip, standalone, dir)	22m 1s
	6h 17m 36s

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