Set kube-cert-agent imagePullPolicy to IfNotPresent for CI

Maybe this will fix kind integration tests? It is what the main
Pinniped deployment does?

Signed-off-by: Andrew Keesler <akeesler@vmware.com>

internal/server/server.go

@@ -241,6 +241,7 @@ func createKubeCertAgentTemplate(cfg *configapi.KubeCertAgentSpec, serverInstall
 				{
 					Name:            "sleeper",
 					Image:           *cfg.Image,
+					ImagePullPolicy: corev1.PullIfNotPresent,
 					Command:         []string{"/bin/sleep", "infinity"},
 					Resources: corev1.ResourceRequirements{
 						Limits: corev1.ResourceList{