kvm: Do not set backing file format of DATADISK in vm start/migration#4800

DaanHoogland merged 2 commits into

apache:4.15apache/cloudstack:4.15from

ustcweizhou:4.15-donot-rebase-datadisk-qcow2ustcweizhou/cloudstack:4.15-donot-rebase-datadisk-qcow2Copy head branch name to clipboard