AzureFile not working with non-root user, unable to upgrade to fixed version of K8S

In the 1.8.x branch until 1.8.5, volumes are mounted as 0x700. Amongst others, Jenkins creates a  `jenkins-user` which accesses the volume, leading to a `permission denied` error.

1.7.9 can be used as a workaround, but I can't downgrade my 1.8.2 cluster to this. 1.8.5 also fixes this, but this is not available on AKS yet.

See https://github.com/kubernetes/kubernetes/pull/54674 for the fix.