This is to align test scripts and playbooks with the recent
merger with the osh-infra repo.
* Get rid of OSH_INFRA_* env variables and
use OSH_* variables wherever necessary
* Update linter job so that playbook runs
the linting commands directly not involving tox
and additional shell script
* Move tools/gate/playbooks/* to playbooks/*
* Cleanup unused playbooks
* Cleanup unused shell scripts
Change-Id: I1913ed613025457d97cf1a4eeca6c2fbda0b72f6
536dccaf5b