salt: Skip etcd role when calling highstate downgrade

When downgrading we need to first downgrade all the nodes and after take
care of the etcd cluster, that why we need to skip `etcd` role when
calling highstate on nodes

salt/metalk8s/orchestrate/deploy_node.sls

@@ -1,6 +1,8 @@
 {%- set node_name = pillar.orchestrate.node_name %}
 {%- set version = pillar.metalk8s.nodes[node_name].version %}
 
+{%- set skip_roles = pillar.metalk8s.nodes[node_name].get('skip_roles', []) %}
+
 {%- if node_name not in salt.saltutil.runner('manage.up') %}
 Deploy salt-minion on a new node:
   salt.state:
@@ -116,6 +118,15 @@ Run the highstate:
     - tgt: {{ node_name }}
     - highstate: True
     - saltenv: metalk8s-{{ version }}
+    {#- Add ability to skip node roles to not apply all the highstate
+         e.g.: Skipping etcd when downgrading #}
+    {%- if skip_roles %}
+    - pillar:
+        metalk8s:
+          nodes:
+            {{ node_name }}:
+              skip_roles: {{ skip_roles }}
+    {%- endif %}
     - require:
       - salt: Set grains
       - salt: Refresh the mine

salt/metalk8s/orchestrate/downgrade/init.sls

@@ -78,6 +78,12 @@ Deploy node {{ node }}:
           {#- Do not drain if we are in single node cluster #}
           skip_draining: True
           {%- endif %}
+        metalk8s:
+          nodes:
+            {{ node }}:
+              # Skip `etcd` role as we take care of etcd cluster after
+              skip_roles:
+                - etcd
     - require:
       - metalk8s_kubernetes: Set node {{ node }} version to {{ dest_version }}
     - require_in: