CA-214975: don't reset VDIs on assume-failed
CA-214975: don't reset VDIs on assume-failed

Since xapi's DB GC's logic to determine whether a host has failed takes a while
to see the first heartbeat from each host, it calls the
host-post-declare-scripts with reason="assume-failed" on each host.

This means that the "assume-failed" logic is called for every slave after every
toolstack start on the master.

Even if "assume-failed" is used on appropriate occasions, resetting the VDIs is
still dangerous because any VMs running on a slave will be treated as not being
attached, which can cause the SM layer to make invalid assumptions, possibly
leading to data loss and corruption.

Signed-off-by: Jonathan Davies <d3af50858a27f644d377a39d1fbd399608163688@citrix.com>
Signed-off-by: Jon Ludlam <e7e3380887a8f95cc9dc4f0d51dedc7e849a287a@citrix.com>
Reviewed-by: Alex Brett <1cb06bfa997a33a00cb43664f08580938a051c48@citrix.com>

jjd27/xen-api,jjd27/xen-api,jjd27/xen-api,jjd27/xen-api,jjd27/xen-api,jjd27/xen-api