[feature] Supprt enabling cpu limit in corends deployment (#10103)

roles/kubernetes-apps/ansible/defaults/main.yml

 ---
 # Limits for coredns
+
+# uncomment the line below to customize the DNS cpu limit value
+# dns_cpu_limit: 300m
 dns_memory_limit: 300Mi
 dns_cpu_requests: 100m
 dns_memory_requests: 70Mi

roles/kubernetes-apps/ansible/templates/coredns-deployment.yml.j2

@@ -65,6 +65,9 @@ spec:
           # guaranteed class. Currently, this container falls into the
           # "burstable" category so the kubelet doesn't backoff from restarting it.
           limits:
+{% if dns_cpu_limit is defined %}
+            cpu: {{ dns_cpu_limit }}
+{% endif %}
             memory: {{ dns_memory_limit }}
           requests:
             cpu: {{ dns_cpu_requests }}