ci: allow ariadne agents to fall back to rpi4

Jenkinsfile

@@ -10,7 +10,6 @@ metadata:
     app: ariadne
 spec:
   nodeSelector:
-    hardware: rpi5
     kubernetes.io/arch: arm64
     node-role.kubernetes.io/worker: "true"
   affinity:
@@ -24,6 +23,11 @@ spec:
                   - titan-06
       preferredDuringSchedulingIgnoredDuringExecution:
         - weight: 100
+          preference:
+            matchExpressions:
+              - key: atlas.bstein.dev/spillover
+                operator: DoesNotExist
+        - weight: 95
           preference:
             matchExpressions:
               - key: kubernetes.io/hostname
@@ -33,6 +37,20 @@ spec:
                   - titan-15
                   - titan-17
                   - titan-19
+        - weight: 85
+          preference:
+            matchExpressions:
+              - key: hardware
+                operator: In
+                values:
+                  - rpi5
+        - weight: 45
+          preference:
+            matchExpressions:
+              - key: hardware
+                operator: In
+                values:
+                  - rpi4
   topologySpreadConstraints:
     - maxSkew: 1
       topologyKey: kubernetes.io/hostname