Add /tmp emptyDir mount for pyroscope.ebpf symbol cache

pyroscope.ebpf creates /tmp/symb-cache at startup. Nix-built
container images have a read-only root filesystem, so /tmp needs
an emptyDir volume mount.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

argocd/manifests/alloy-profiling-ringtail/daemonset.yaml

@@ -44,6 +44,8 @@ spec:
               mountPath: /etc/alloy
             - name: data
               mountPath: /var/lib/alloy/data
+            - name: tmp
+              mountPath: /tmp
           securityContext:
             privileged: true
       tolerations:
@@ -54,3 +56,5 @@ spec:
             name: alloy-profiling-config
         - name: data
           emptyDir: {}
+        - name: tmp
+          emptyDir: {}