ovirt_vnic_profile: Fix issue in resetting the network filter (#53392)

Currently, there is no way to reset the network profile of vNIC profiles
to "No Network Filter". To reset the vNIC profile, we have to pass an
None value to "types.NetworkFilter". The patch allows to reset it by
passing empty string ('') to "network_filter".

lib/ansible/modules/cloud/ovirt/ovirt_vnic_profile.py

@@ -169,7 +169,7 @@ class EntityVnicPorfileModule(BaseModule):
 
     def __get_network_filter_id(self):
         nf_service = self._connection.system_service().network_filters_service()
-        return get_id_by_name(nf_service, self.param('network_filter'))
+        return get_id_by_name(nf_service, self.param('network_filter')) if self.param('network_filter') else None
 
     def build_entity(self):
         return otypes.VnicProfile(
@@ -191,7 +191,7 @@ class EntityVnicPorfileModule(BaseModule):
             qos=otypes.Qos(id=self.__get_qos_id())
             if self.param('qos') else None,
             network_filter=otypes.NetworkFilter(id=self.__get_network_filter_id())
-            if self.param('network_filter') else None
+            if self.param('network_filter') is not None else None
         )
 
     def update_check(self, entity):
@@ -209,7 +209,7 @@ class EntityVnicPorfileModule(BaseModule):
             equal(self.param('migratable'), getattr(entity, 'migratable', None)) and
             equal(self.param('pass_through'), entity.pass_through.mode.name) and
             equal(self.param('description'), entity.description) and
-            equal(self.param('network_filter'), entity.network_filter.name) and
+            equal(self.param('network_filter'), getattr(entity.network_filter, 'name', None)) and
             equal(self.param('qos'), entity.qos.name) and
             equal(self.param('port_mirroring'), getattr(entity, 'port_mirroring', None))
         )