CA-174968: XenAPI SR.scan: call both SMAPI SR.scan and SR.stat
CA-174968: XenAPI SR.scan: call both SMAPI SR.scan and SR.stat

The SMAPIv1 backends update all SR fields in `SR.scan`, whereas
the SMAPIv2 and SMAPIv3 clearly separate the `SR.scan` (list VDIs)
from the `SR.stat` (query SR properties). To avoid confusing clients,
the XenAPI `SR.scan` should do both functions.

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

guard163/xen-api,simonjbeaumont/xen-api,jjd27/xen-api,salvocambria/xen-api,euanh/xen-api,srowe/xen-api,jjd27/xen-api,simonjbeaumont/xen-api,salvocambria/xen-api,Frezzle/xen-api,jjd27/xen-api,srowe/xen-api,thomassa/xen-api,Frezzle/xen-api,anoobs/xen-api,vasilenkomike/xen-api,simonjbeaumont/xen-api,guard163/xen-api,salvocambria/xen-api,djs55/xen-api,agimofcarmen/xen-api,anoobs/xen-api,thomassa/xen-api,vasilenkomike/xen-api,guard163/xen-api,Frezzle/xen-api,robertbreker/xen-api,srowe/xen-api,Frezzle/xen-api,vasilenkomike/xen-api,salvocambria/xen-api,agimofcarmen/xen-api,robertbreker/xen-api,robertbreker/xen-api,jjd27/xen-api,agimofcarmen/xen-api,anoobs/xen-api,robertbreker/xen-api,guard163/xen-api,simonjbeaumont/xen-api,Frezzle/xen-api,thomassa/xen-api,euanh/xen-api,euanh/xen-api,agimofcarmen/xen-api,jjd27/xen-api,rafalmiel/xen-api,simonjbeaumont/xen-api,agimofcarmen/xen-api,euanh/xen-api,anoobs/xen-api,rafalmiel/xen-api,djs55/xen-api,salvocambria/xen-api,salvocambria/xen-api,djs55/xen-api,guard163/xen-api,vasilenkomike/xen-api,simonjbeaumont/xen-api,rafalmiel/xen-api,anoobs/xen-api,anoobs/xen-api,djs55/xen-api,euanh/xen-api,vasilenkomike/xen-api,thomassa/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,robertbreker/xen-api,rafalmiel/xen-api,agimofcarmen/xen-api,thomassa/xen-api,euanh/xen-api,djs55/xen-api,guard163/xen-api,srowe/xen-api,srowe/xen-api,vasilenkomike/xen-api,robertbreker/xen-api,thomassa/xen-api,djs55/xen-api,jjd27/xen-api