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.

docs/calico.md

@@ -1,11 +1,5 @@
 # Calico
 
-N.B. **Version 2.6.5 upgrade to 3.1.1 is upgrading etcd store to etcdv3**
-
-If you create automated backups of etcdv2 please switch for creating etcdv3 backups, as kubernetes and calico now uses etcdv3
- After migration you can check `/tmp/calico_upgrade/` directory for converted items to etcdv3.
- **PLEASE TEST upgrade before upgrading production cluster.**
-
 Check if the calico-node container is running
 
 ```ShellSession
@@ -20,24 +14,12 @@ The **calicoctl.sh** is wrap script with configured acces credentials for comman
 calicoctl.sh node status
 ```
 
-or for versions prior to *v1.0.0*:
-
-```ShellSession
-calicoctl.sh status
-```
-
 * Show the configured network subnet for containers
 
 ```ShellSession
 calicoctl.sh get ippool -o wide
 ```
 
-or for versions prior to *v1.0.0*:
-
-```ShellSession
-calicoctl.sh pool show
-```
-
 * Show the workloads (ip addresses of containers and their location)
 
 ```ShellSession
@@ -50,12 +32,6 @@ and
 calicoctl.sh get hostEndpoint -o wide
 ```
 
-or for versions prior *v1.0.0*:
-
-```ShellSession
-calicoctl.sh endpoint show --detail
-```
-
 ## Configuration
 
 ### Optional : Define datastore type