Avoid duplicate stdout on playbook failures

[ssbarnea]

Newer run_command does print stdout/stderr, so there is no need to, print them again in case of failure. We now display the error code and the original command the produced it.

Example output:

$ molecule converge                                                                                               [12:55:46]
--> Found config file /Users/ssbarnea/c/a/molecule/.config/molecule/config.yml
--> Test matrix
---
default:
  - dependency
  - create
  - prepare
  - converge
--> Scenario: 'default'
--> Action: 'dependency'
Skipping, missing the requirements file.
Skipping, missing the requirements file.
--> Scenario: 'default'
--> Action: 'create'
Skipping, instances already created.
--> Scenario: 'default'
--> Action: 'prepare'
Skipping, prepare playbook not configured.
--> Scenario: 'default'
--> Action: 'converge'

PLAY [Converge] ****************************************************************

TASK [Gathering Facts] *********************************************************
fatal: [localhost]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: root@localhost: Permission denied (publickey,password,keyboard-interactive).", "unreachable": true}

PLAY RECAP *********************************************************************
localhost                  : ok=0    changed=0    unreachable=1    failed=0    skipped=0    rescued=0    ignored=0

ERROR: Ansible return code was 4, command was ansible-playbook --inventory /Users/ssbarnea/.cache/molecule/molecule/default/inventory --skip-tags molecule-notest,notest /Users/ssbarnea/c/a/molecule/molecule/default/converge.yml
Time: 0h:00m:03s