Set traefik resource requests so HPAs can scale (#520)

Both traefik HPAs report `ScalingActive False: missing request for cpu` because the chart values set no container resources, so the CPU-utilisation metric can't be computed and neither Deployment ever scales.

- traefik-external requests 200m CPU / 128Mi, memory limit 512Mi
- traefik-internal requests 500m CPU / 256Mi, memory limit 1Gi
- No CPU limits, to avoid throttling the proxy
- The chart derives GOMEMLIMIT (90% of the memory limit) from the new limits

Reviewed-on: #520
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

apps/overlays/au-syd1/traefik-system/values-external.yaml

@@ -74,6 +74,13 @@ autoscaling:
     kind: Deployment
     name: "{{ template \"traefik.fullname\" . }}"
 
+resources:
+  requests:
+    cpu: 200m
+    memory: 128Mi
+  limits:
+    memory: 512Mi
+
 persistence:
   enabled: false
 

apps/overlays/au-syd1/traefik-system/values-internal.yaml

@@ -72,6 +72,13 @@ autoscaling:
     kind: Deployment
     name: "{{ template \"traefik.fullname\" . }}"
 
+resources:
+  requests:
+    cpu: 500m
+    memory: 256Mi
+  limits:
+    memory: 1Gi
+
 persistence:
   enabled: false