Containerd in e2e image was using native one in ubuntu, it should be updated to the latest release.
And add proxy cache py-tests including pull image/manifest list by docker and ctr CLI.
Signed-off-by: danfengliu <danfengl@vmware.com>
1. Fix#5102 by checking the existence of name when creating/editing replication rule
2. Add unique constraint to the name of replication policy and target
3. Fix bugs of testing library
Signed-off-by: Wenkai Yin <yinw@vmware.com>