calico: don't set calico-node cpu limits by default (#11914)

Upstream calico isn't doing that, and:
- this can cause throttling
- the cpu needed by calico is very cluster / workload dependent
- missing cpu limits will not starve other pods (unlike missing memory
  requests), because the kernel scheduler will still gives priority to
  other process in pods not exceeding their requests

roles/network_plugin/calico/templates/calico-node.yml.j2

@@ -352,7 +352,9 @@ spec:
             privileged: true
           resources:
             limits:
+{% if calico_node_cpu_limit != "0" %}
               cpu: {{ calico_node_cpu_limit }}
+{% endif %}
               memory: {{ calico_node_memory_limit }}
             requests:
               cpu: {{ calico_node_cpu_requests }}

roles/network_plugin/calico_defaults/defaults/main.yml

@@ -58,7 +58,7 @@ calico_felix_floating_ips: Disabled
 
 # Limits for apps
 calico_node_memory_limit: 500M
-calico_node_cpu_limit: 300m
+calico_node_cpu_limit: "0"
 calico_node_memory_requests: 64M
 calico_node_cpu_requests: 150m
 calico_felix_chaininsertmode: Insert