stack/erp5: remove some unused eggs

erp5.recipe.w3validator is not installed, it was just a version pin
because when running buildout updating the software needs a version
pin, by now all softwares must have been updated.
7 jobs for 1.0
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

passed ERP5.StandaloneDeploymentScriptTest-Debian.Stretch

passed SlapOS.Eggs.UnitTest-Master.Python3

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Stretch