fix stat virt-vnc and virt-serial0 return error

[huyinhou]

the default base image for virt-handler is centos, which workdir is /. but we use a custom debian:buster as the base image, which workdir is /root.

when we run virtctl -n test vnc vm1, it reports an error:
Can't access VMI vm1: Internal error occurred: dialing virt-handler: websocket: bad handshake
I digged into this problem, and found that the virt-vnc sock path in getUnixSocketPath is proc/3484989/root/var/run/kubevirt-private/a44829ef-d44c-4a64-bf8a-2bcf274bad12/virt-vnc without leading '/'.
when it runs os.Stat with this path, it will return an error "no such file or directory".

so, I think maybe we can add a leading '/' to make an absolute path, it will work no matter what the workdir of the virt-handler image is.

Signed-off-by: huyinhou [email protected]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Release note:

connect VM vnc failed when virt-launcher work directory is not /

[kubevirt-bot]

Hi @huyinhou. Thanks for your PR.

I'm waiting for a kubevirt member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[xpivarc]

/approve
/test all

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: xpivarc

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [xpivarc]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[huyinhou]

/retest

[kubevirt-bot]

@huyinhou: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[rmohr]

/lgtm

[brianmcarey]

/test pull-kubevirt-fossa