- removes duplicate keys from yaml files by assuming that the last
one was the desired one (matches current loader behavior)
- prevent regressions by activating yaml lint rule that detects them
(yaml skip was silencing all yaml checks, so the long list seen
is in fact shorter than just 'yaml')
- includes sorting of some of the keys, was needed in order to spot
the duplicates.
Change-Id: Idf5c0041a0c6d3ed7d5d49fb68be856719916663