Set runAsUser uid for nonroot distroless image

Port of tektoncd/pipeline#3342:

The distroless nonroot image define a user with the uid 65532. The
deployment should use that uid to make sure it works anywhere.

Author: dibyom

base/300-deployment.yaml

@@ -50,6 +50,7 @@ spec:
       volumes: []
       securityContext:
         runAsNonRoot: true
+        runAsUser: 65532
       containers:
         - name: tekton-dashboard
           image: dashboardImage