fix(multitanent): `stop_resources when` `setUp` fails
fix(multitanent): `stop_resources when` `setUp` fails

if `setUp` is failing for some reason, stop resources was failing like the following:
```
Traceback (most recent call last):
   File ".../sdcm/utils/operator/multitenant_common.py", line 135, in setUp
     super().setUp()
   File ".../sdcm/tester.py", line 158, in wrapper
     args[0].tearDown()
   File ".../sdcm/tester.py", line 2680, in tearDown
     self.stop_resources()
   File ".../sdcm/utils/operator/multitenant_common.py", line 145, in stop_resources
     objects=[[tenant] for tenant in self.tenants],
AttributeError: 'LongevityOperatorMultiTenantTest' object has no attribute 'tenants'
```

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests