[conn_graph] improve graph facts collector

[yxieca]

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

What is the motivation for this PR?

Nightly test are all failing due to regression in conn_graph_facts.py.

How did you do it?

• Collect first element of list.
• Collect full variable for non-list variables.

Signed-off-by: Ying Xie [email protected]

How did you verify/test it?

Run test on physical DUT. Without fix:

    if (res.is_failed or 'exception' in res) and not module_ignore_errors:

      raise RunAnsibleModuleFail("run module {} failed".format(self.module_name), res)

E RunAnsibleModuleFail: run module conn_graph_facts failed, Ansible Results =>
E {
E "changed": false,
E "failed": true,
E "invocation": {
E "module_args": {
E "anchor": null,
E "filename": "/var/src/sonic-mgmt/tests/common/fixtures/../../../ansible/files/starlab_connection_graph.xml",
E "filepath": null,
E "host": "str-dx010-acs-1",
E "hosts": null
E }
E },
E "msg": "Traceback (most recent call last):\n File "/tmp/ansible_conn_graph_facts_payload_PAqL5h/main.py", line 348, in main\n results = {k: v[0] for k, v in results.items()}\n File "/tmp/ansible_conn_graph_facts_payload_PAqL5h/main.py", line 348, in \n results = {k: v[0] for k, v in results.items()}\nKeyError: 0\n"
E }

With the fix, test passes.