Revert "Add a feature flag by default for dom0 (/control/feature-shutdown-request) to cause xenops to use the existing shutdown-request protocol for dom0."
Revert "Add a feature flag by default for dom0 (/control/feature-shutdown-request) to cause xenops to use the existing shutdown-request protocol for dom0."

I suspect this has exposed a race in the VIF hotplug scripts (and possibly VBD ones too).

This reverts commit 6358ed998af383d1565e9ea9e6b72bb08b1d98de.

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