tarmak clusters apply --infrastructure-only still runs convergence check

[dippynark]

Is this a BUG REPORT or FEATURE REQUEST?:

/kind bug

What happened: When upgrading the master and worker instance pools tarmak clusters apply --infrastructure-only ran the convergence code even though there were infrastructure changes which seems to contradict this issue

What you expected to happen: tarmak clusters apply --infrastructure-only should not check for convergence

How to reproduce it (as minimally and precisely as possible): follow https://playbooks.jetstack.io/tarmak/upgrading-instance-pool.html after changing the sizes of all instance pools

Environment:

• Kubernetes version (use kubectl version): 1.11.5
• Tarmak version: 0.6.0

[dippynark]

I think we need a check here to not run the convergence code when infrastructure only has been specified. However, we want it so if a user explicitly asks for wait for convergence even when specifying infrastructure only then it happens as it's a useful way of checking whether all wings are running the latest puppet without triggering them. That is useful at the end of the playbook referenced in the issue