Fix Attribute Error when Metadata is Missing

[sven-rosenzweig]

In some cases, metadata information (including age) may be missing for an OpenStack ID. Previously, this caused an exception, leading to an aborted sync.

Since the sync is a preventive measure to synchronize objects of a certain age — most likely unchanged from OpenStack's perspective — this commit ensures the process continues even when metadata is absent.

To improve debugging, we now log the resource_type and os_id when metadata is missing.

[sven-rosenzweig]

With this commit we should get rid of the following exception.

[github-actions]

Name                                                                      Stmts   Miss  Cover
---------------------------------------------------------------------------------------------
networking_nsxv3/api/rpc.py                                                 233    110    53%
networking_nsxv3/common/config.py                                            16      0   100%
networking_nsxv3/common/constants.py                                         23      0   100%
networking_nsxv3/common/locking.py                                           35     11    69%
networking_nsxv3/common/synchronization.py                                  180     49    73%
networking_nsxv3/db/db.py                                                    94     19    80%
networking_nsxv3/extensions/nsxtoperations.py                               104     40    62%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/agent.py                   162     52    68%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/cli.py                     299    195    35%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/client_nsx.py              187     49    74%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/constants_nsx.py             6      0   100%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/extensions/firewall.py      27      0   100%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/provider.py                169     10    94%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/provider_nsx_policy.py     765    113    85%
networking_nsxv3/plugins/ml2/drivers/nsxv3/agent/realization.py             203     33    84%
networking_nsxv3/plugins/ml2/drivers/nsxv3/driver.py                        129     74    43%
networking_nsxv3/prometheus/exporter.py                                      19      5    74%
networking_nsxv3/services/logapi/drivers/nsxv3/driver.py                     41      1    98%
networking_nsxv3/services/qos/drivers/nsxv3/qos.py                           34      4    88%
networking_nsxv3/services/trunk/drivers/nsxv3/trunk.py                       71      3    96%
---------------------------------------------------------------------------------------------
TOTAL                                                                      2797    768    73%