[virtlet] Refactor virtlet part

- Remove virtlet roles
- Remove virtlet fixtures due virtlet officially installed as
addon if option is enabled
- Move virtlet core test functions under k8smanager.py
- Add show_step into virtlet tests
- Add checks that virtlet is enabled to the beginning of tests

Change-Id: Ibfb499b29727b367afafc68fa13199db13bcccdf
diff --git a/tcp_tests/templates/virtual-mcp11-k8s-calico/k8s.yaml b/tcp_tests/templates/virtual-mcp11-k8s-calico/k8s.yaml
index 0122003..182453a 100644
--- a/tcp_tests/templates/virtual-mcp11-k8s-calico/k8s.yaml
+++ b/tcp_tests/templates/virtual-mcp11-k8s-calico/k8s.yaml
@@ -21,7 +21,7 @@
      salt --hard-crash --state-output=mixed --state-verbose=False -C 'I@kubernetes:pool' state.sls kubernetes.pool;
      salt --hard-crash --state-output=mixed --state-verbose=False -C 'I@kubernetes:pool' cmd.run 'calicoctl node status';
   node_name: {{ HOSTNAME_CFG01 }}
-  retry: {count: 1, delay: 5}
+  retry: {count: 3, delay: 5}
   skip_fail: false
 
 - description: Setup NAT for Calico