[CA-60540] Fix forced SR/VDI import.
[CA-60540] Fix forced SR/VDI import.

When doing a forced VM metadata import, xapi will now skip over any
missing SRs and their VDIs instead of causing the import to fail.

Signed-off-by: John Else <37b74501daa612e48fea94f9846ed4ddeb6a8f07@citrix.com>

johnelse/xcp-rrdd,johnelse/xcp-rrdd,koushikcgit/xcp-networkd,sharady/xcp-networkd,djs55/xcp-networkd,djs55/xcp-rrdd,simonjbeaumont/xcp-rrdd,simonjbeaumont/xcp-rrdd,djs55/xcp-networkd,djs55/squeezed,koushikcgit/xcp-rrdd,djs55/xcp-rrdd,koushikcgit/xcp-networkd,koushikcgit/xcp-rrdd,robhoes/squeezed,koushikcgit/xcp-rrdd,sharady/xcp-networkd