[xapi]: don't push VM metadata to xenopsd if the VM is shutting down
[xapi]: don't push VM metadata to xenopsd if the VM is shutting down

This is needed because the xenops VM is 'transient' meaning that it
disappears on permanent shutdown, and this is the signal for xapi to
set the power_state to Halted. If a xapi event occurs and xapi reloads
the VM configuration after it has disappeared, the VM will have its
power_state set to Running, tripping the assert in VM.shutdown

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

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