Don't mount persistent partition during upgrades

[mudler]

We don't overwrite files in there during upgrades, honor user configuration.

I've started to see the following in our test runs:

 Downloading quay.io/costoolkit/releases-opensuse:cos-system-0.5.1 to /usr/local/tmp/rootfs
 Pulled: sha256:77df78ffa40fadad89a853d9d4a7e158774813440a582cd458fa90ebc15f711c quay.io/costoolkit/releases-opensuse:cos-system-0.5.1
 Size: 240.1MiB
rsync: rsync_xal_set: lremovexattr("/tmp/upgrade/oem","security.selinux") failed: Permission denied (13)
rsync: rsync_xal_set: lremovexattr("/tmp/upgrade/usr/local","security.selinux") failed: Permission denied (13)
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1189) [sender=3.1.3]
: Process exited with status 23
[AfterEach] cOS Upgrade tests - Images unsigned
  /Users/runner/work/cOS-toolkit/cOS-toolkit/tests/upgrades-images-unsigned/upgrade_test.go:18

We don't need to actually mount /oem and /usr/local, but instead we should just honor user configuration/data.

See also https://pipelines.actions.githubusercontent.com/7NrIHdq3eLtbIIhKdS1B3XLJn6nB7zCt3yDXY4xKbkAggKCwdc/_apis/pipelines/1/runs/3177/signedlogcontent/117?urlExpires=2021-06-16T08%3A36%3A36.2919869Z&urlSigningMethod=HMACV1&urlSignature=Jku5NUysoGK3sBUSQh4V4aNKx93Msr3VNmmMBEzTBzM%3D

Signed-off-by: Ettore Di Giacinto edigiacinto@suse.com

[davidcassany]

@mudler I'd say this is safe to merge. See all non nonsquashfs tests passed.