Resolve ansible-playbook command before execution

[PaulFarault]

Which issue(s) this PR fixes

Fixes None

Additional comments

• use += operator to compose the command
• resolve ansible-playbook command before executing the script

Agreements

• I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004.
• I hereby agree to grant TOSIT a copyright license to use my contributions.

[sergkudinov]

Behavior of tdp deploy is wrong when it is interrupted by the error of missing ansible.

The problem is that the status of the current deployment is changed to RUNNING, but the issue caused this is of a "global" scope, because we shouldn't run the deployment until we have checked all the prerequisites.

To reproduce, first simulate the absence of ansible-playbook in PATH, and then run:

tdp plan dag
tdp deploy --mock-deploy
tdp browse

I am not sure whether it is in the scope of this PR, probably not.

[PaulFarault]

In my understanding you are mentioning 2 different issues:

• The status that stays RUNNING after a failure, which will be handled in Database left in an incorect state if interrupting an ongoing deployment #340
• Requirements testing, which we should discuss at some point (no existing issue)

I agree that it is not in the scope of this PR.