ci(lesavka): avoid overloaded rpi5 runner

Jenkinsfile

@@ -15,6 +15,23 @@ spec:
     hardware: rpi5
     kubernetes.io/arch: arm64
     node-role.kubernetes.io/worker: "true"
+  affinity:
+    nodeAffinity:
+      requiredDuringSchedulingIgnoredDuringExecution:
+        nodeSelectorTerms:
+          - matchExpressions:
+              - key: kubernetes.io/hostname
+                operator: NotIn
+                values:
+                  - titan-04
+      preferredDuringSchedulingIgnoredDuringExecution:
+        - weight: 100
+          preference:
+            matchExpressions:
+              - key: kubernetes.io/hostname
+                operator: In
+                values:
+                  - titan-11
   containers:
     - name: rust-ci
       image: registry.bstein.dev/bstein/lesavka-ci@sha256:699ff0a2b4461f8627fcc19353eae0dee49500486eb1819287b5713ad239c13f