catalog: use the ownerBy relation to display owners

Co-authored-by: blam <ben@blam.sh>

plugins/catalog/src/components/AboutCard/AboutCard.tsx

@@ -14,7 +14,12 @@
  * limitations under the License.
  */
 
-import { Entity, ENTITY_DEFAULT_NAMESPACE } from '@backstage/catalog-model';
+import {
+  Entity,
+  ENTITY_DEFAULT_NAMESPACE,
+  RELATION_OWNED_BY,
+  serializeEntityRef,
+} from '@backstage/catalog-model';
 import {
   Card,
   CardContent,
@@ -139,7 +144,20 @@ export function AboutCard({ entity, variant }: AboutCardProps) {
           </AboutField>
           <AboutField
             label="Owner"
-            value={entity?.spec?.owner as string}
+            value={entity?.relations
+              ?.filter(r => r.type === RELATION_OWNED_BY)
+              .map(({ target: { kind, name, namespace } }) =>
+                // TODO(Rugvip): we want to provide some utils for this
+                serializeEntityRef({
+                  kind,
+                  name,
+                  namespace:
+                    namespace === ENTITY_DEFAULT_NAMESPACE
+                      ? undefined
+                      : namespace,
+                }),
+              )
+              .join(', ')}
             gridSizes={{ xs: 12, sm: 6, lg: 4 }}
           />
           <AboutField