Due to the way of how dynamic_inventory parses groups, usage of
`haproxy_hosts` which are eventually mapped to `haproxy` lead bare
metal hosts to be also a part of `haproxy_all` group, which might be not
expected or anticipated.
Change-Id: Ib1199236a6dfecb47b5840f04cb4b1486cc2f6a6
c5fbcbfbbb