shared/tester: Return failure if any test failed
shared/tester: Return failure if any test failed

This makes sure tester can be used for unit tests that requires proper
return in case of failure.

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