chore(deps): update goharbor/harbor-portal docker tag to v2.15.0

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| goharbor/harbor-exporter | minor | `v2.14.3` → `v2.15.0` |

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Reviewed-on: #4780
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clusters/cl01tl/helm/harbor/values.yaml

@@ -41,7 +41,7 @@ harbor:
   portal:
     image:
       repository: goharbor/harbor-portal
-      tag: v2.14.3
+      tag: v2.15.0
     replicas: 2
   core:
     image:
@@ -94,7 +94,7 @@ harbor:
   exporter:
     image:
       repository: goharbor/harbor-exporter
-      tag: v2.14.3
+      tag: v2.15.0
     replicas: 2
 postgres-18-cluster:
   mode: recovery