Speed up buildkite tests
Speed up buildkite tests

Use the minimal container for the chefstyle tests
Remove extra env vars that were for travis
Exclude gem groups we don't care about
Parallelize the bundler commands

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

gene1wood/chef,higanworks/chef,mwrock/chef,tas50/chef-1,MsysTechnologiesllc/chef,jaymzh/chef,jaymzh/chef,mattray/chef,mattray/chef,mattray/chef,mwrock/chef,nvwls/chef,higanworks/chef,MsysTechnologiesllc/chef,MsysTechnologiesllc/chef,MsysTechnologiesllc/chef,higanworks/chef,gene1wood/chef,mwrock/chef,mwrock/chef,jaymzh/chef,higanworks/chef,chef/chef,mattray/chef,tas50/chef-1,nvwls/chef,chef/chef,nvwls/chef,chef/chef,higanworks/chef,tas50/chef-1,gene1wood/chef,nvwls/chef,nvwls/chef,gene1wood/chef,chef/chef,tas50/chef-1,jaymzh/chef,mattray/chef,nvwls/chef