obexd: Returns OBEX service unavailable when ebook async get contacts fails
obexd: Returns OBEX service unavailable when ebook async get contacts fails

PullvCardListing shall return OBEX error service unavailable when
ebook can process a valid contact query. Given the available error
codes for PBAP, service unvailable is the code more suitable for
this scenario.

ComputeCycles/bluez,pkarasev3/bluez,pkarasev3/bluez,pkarasev3/bluez,mapfau/bluez,ComputeCycles/bluez,ComputeCycles/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,silent-snowman/bluez,mapfau/bluez,mapfau/bluez,ComputeCycles/bluez,silent-snowman/bluez,pkarasev3/bluez