Change AIX to use only one build

The AIX 6.1 build runs fine on AIX 7.1 and 7.2.

Things that need to be done for this:

• Update ci-job-configs so we only build AIX 6.1
• Update beaker to install a 6.1 AIX RPM on all AIX versions
• Update pe-repo to handle the 6.1 AIX RPM
• Update the puppet_agent module to handle the 6.1 AIX RPM

Currently this work includes doing migration of classification for the pe_repo stuff - I'm not entirely sure that's viable, and we may want to instead keep the old classes around for compatibility and encourage users to migrate manually through documentation / deprecation warnings.