Remove HHVM testing from BRATs pipeline
Remove HHVM testing from BRATs pipeline

- HHVM support has been removed from the PHP buildpack for quite some time

[#113172267]

cloudfoundry/buildpacks-ci,orange-cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,orange-cloudfoundry/buildpacks-ci,orange-cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci,cloudfoundry/buildpacks-ci