Eventually, we will want to start migrating to a latest version of Vega. Before we complete that, we need to deprecate and drop support for Vega 1.5 so we will not have a huge technical debt of supporting three Vega version (1.5, 2.6, 5.13).
@VulpesVulpes825 cleaned up the remaining Vega 1.5 graphs on `itwiki` and theoretically there aren’t many Vega 1.0 graph left on the main namespace in the rest of the Wikimedia Project.
The goal of this task is to flush out any last remaining usage of Vega 1.5 across the Wikimedia projects, migrate them to 2.6 definitions and then remove support for Vega 1.5.
[] announce in tech news this will happen
[] make initial measure of the prevalence of remaining usage of Vega 1.5 and identify wiki and templates needing support for migration.
[] flush out straggles by logging client side errors
[] drop Vega 1.5 and mop up.