labs: Enable  MinimalPuppetAgent collector on all nodes

This declares the python-yaml package, which surprisingly
isn't declared explicitly in anything else that runs on labs.

This collects only:
    - Time since last puppet run
    - Total time it took for puppet to run

Change-Id: I74239d0e502d9f6ac336137331511c8cb96e92f1
Merge "labs: Enable  MinimalPuppetAgent collector on all nodes" into production