Add 7 nodes SRv6 testbed configuration based on Force 10 hwsku (sonic-net#15908)

In sonic-net#15349 and sonic-net#15723 , the 7-nodes testbed for SRv6 based on Cisco VS hwsku was added with the corresponding tests. In this PR, a testbed with similar config to the cisco one, but based on Force 10 hwsku, is introduced.

The cisco vs testbed requires specific SONiC image and data plane emulation toolset from Cisco to work. Therefore, for the sake of testing the control plane only using SONiC images with the vs hwsku, this testbed is added.

Additionally, tests for SRv6 that don't require data plane (i.e. non-traffic-check cases) are enabled for the new Force 10 testbed.

What is the motivation for this PR?
Enable the control plane test for SRv6 with a vs hwsku, without any specific emulation software.

How did you do it?
Duplicate the configuration from the cisco vs testbed, and modify it for Force 10 VS hwsku.

How did you verify/test it?
SRv6 functionality was tested manually first: IPv4 routes were injected from the PTF mimicing CE devices into one of the PE devices, and SRv6 encapsulation enabled routes were observed on other PE devices. Therefore, those routes were successfully propagated via BGP.

The test cases introduced from sonic-net#15723 passed, except the ones that require the data plane which isn't available currently with a vs hwsku.

Any platform specific information?
The DUT and cEOS images were built from https://github.com/eddieruan-alibaba/sonic-buildimage , not from sonic-net/sonic-sonic-buildimage .

Supported testbed topology if it's a new test case?
Not applicable.

Documentation
https://github.com/sonic-net/sonic-mgmt/blob/master/docs/testplan/srv6/SRv6-phoenixwing-ptf-testplan.md

Signed-off-by: Charlie Jiang <w@chariri.moe>

Author: cqjjjzr

ansible/lab

@@ -234,3 +234,13 @@ sonic_cisco_vs:
       hwsku: cisco-8101-p4-32x100-vs
       ansible_host: 10.250.0.125
       ansible_hostv6: fec0::ffff:afa:13
+    vlab-c-02:
+      ansible_host: 10.250.0.125
+      ansible_hostv6: fec0::ffff:afb:8
+      type: kvm
+      hwsku: Force10-S6000
+      serial_port: 9025
+      ansible_password: password
+      ansible_user: admin
+      ansible_ssh_user: admin
+      ansible_altpassword: admin

ansible/roles/vm_set/tasks/docker.yml

@@ -1,8 +1,3 @@
-- name: Add docker official GPG key
-  apt_key: url=https://download.docker.com/linux/ubuntu/gpg state=present
-  become: yes
-  environment: "{{ proxy_env | default({}) }}"
-
 - name: Check docker repository
   find:
     paths: /etc/apt/sources.list.d/
@@ -19,6 +14,12 @@
     msg: "Docker repository does not exist"
   when: docker_repo.matched == 0
 
+- name: Add docker official GPG key
+  apt_key: url=https://download.docker.com/linux/ubuntu/gpg state=present
+  become: yes
+  environment: "{{ proxy_env | default({}) }}"
+  when: docker_repo.matched == 0
+
 - name: Add docker repository for 16.04
   apt_repository:
     repo: deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable