This edge release fixes linkerd check and the helm charts to explicitly indicate that the minimum Kubernetes version is 1.17.0. Prior to this change, there was no validation or enforcement from linkerd check or helm to meet this minimum requirement. This edge also improves `check` functionality for extensions by adding the `-oshort` flag, and prevents duplicate policy resources from being created for linked multicluster services. * Moved service mirror policy into multicluster base chart * Added `-oshort` flag for extension `check` commands * Updated minimum kubernetes version to 1.17.0 * Removed unused `crtExpiry` template parameter from helm charts * Fixed multicluster gateway name for ServerAuthorization * Added `priorityClassName` to the helm charts to configure control plane components