Goal:
As a cluster administrator, I want OpenShift to include a recent HAProxy version, so that I have the latest available performance and security fixes.  

 Description:
We should strive to follow upstream HAProxy releases by bumping the HAProxy version that we ship in OpenShift with every 4.y release, so that OpenShift benefits from upstream performance and security fixes, and so that we avoid large version-number jumps when an urgent fix necessitates bumping to the latest HAProxy release.  This bump should happen as early as possible in the OpenShift release cycle, so as to maximize soak time.   

For OpenShift 4.13, this means bumping to 2.6.