Calico upgrade path validation and old version cleanup (#6733)

* calico: add constant calico_min_version_required

and verify current deployed version against it.

* calico: remove upgrade support with data migration

The tool was used pre v3.0.0 and is no longer needed.

* calico: remove old version support from tasks

* calico: remove old ver support from policy ctrl

* calico: remove old ver support from node

* canal: remove old ver support

* remove unused calicoctl download checksums

calico_min_version_required is the oldest version that can be installed
Older versions can be removed.

roles/network_plugin/calico/tasks/check.yml

@@ -36,36 +36,3 @@
     msg: "IP in IP and VXLAN mode is mutualy exclusive modes"
   when:
     - "calico_vxlan_mode in ['Always', 'CrossSubnet']"
-
-- name: "Get current version of calico cluster version"
-  shell: "set -o pipefail && {{ bin_dir }}/calicoctl.sh version  | grep 'Cluster Version:' | awk '{ print $3}'"
-  args:
-    executable: /bin/bash
-  register: calico_version_on_server
-  async: 10
-  poll: 3
-  run_once: yes
-  changed_when: false
-  failed_when: false
-
-- name: "Determine if calico upgrade is needed"
-  block:
-    - name: "Check that calico version is enough for upgrade"
-      assert:
-        that:
-          - calico_version_on_server.stdout is version('v2.6.5', '>=')
-        msg: "Your version of calico is not fresh enough for upgrade"
-      when: calico_upgrade_enabled
-
-    - name: "Set upgrade flag when version needs to be updated"
-      set_fact:
-        calico_upgrade_needed: True
-      when:
-        - calico_version_on_server.stdout is version('v2.6.5', '>=')
-        - calico_version_on_server.stdout is version('v3.0.0', '<')
-
-  when:
-    - calico_version_on_server.stdout is defined
-    - calico_version_on_server.stdout
-    - inventory_hostname == groups['kube-master'][0]
-  run_once: yes