proxy: remove workaround for old broken clients
proxy: remove workaround for old broken clients

this has been fixed for a long time
(https://bz.apache.org/bugzilla/show_bug.cgi?id=38864) and the
workaround documented by @niq http://www.apachetutor.org/admin/reverseproxies
hasn't been necessary for a long time.

traylenator/puppetlabs-apache,guegue/puppetlabs-apache,digitalmediacenter/puppetlabs-apache,puppetlabs/puppetlabs-apache,puppetlabs/puppetlabs-apache,svanhart/puppetlabs-apache,buzzdeee/puppetlabs-apache,bmjen/puppetlabs-apache,samuelb/puppetlabs-apache,guegue/puppetlabs-apache,digitalmediacenter/puppetlabs-apache,FlatKey/puppetlabs-apache,bmjen/puppetlabs-apache,traylenator/puppetlabs-apache,dzmitryv/puppetlabs-apache,samuelb/puppetlabs-apache,dzmitryv/puppetlabs-apache,gerhardsam/puppetlabs-apache,yakatz/puppetlabs-apache,eputnam/puppetlabs-apache,yakatz/puppetlabs-apache,eputnam/puppetlabs-apache,buzzdeee/puppetlabs-apache,svanhart/puppetlabs-apache,gerhardsam/puppetlabs-apache,FlatKey/puppetlabs-apache