From both a recent conversation with @daniel and per {T200375}, it seems that Pingback should be updated to use the Event Platform. This migration is a little more complicated as the event producer doesn't use EventLogging. This is because the instrument needs to run during installation when extensions aren't loaded.
==== TODO
Per {T259163}:
[x] Create /analytics/legacy/ schema
** https://gerrit.wikimedia.org/r/c/938814
[] Edit-protect https://meta.wikimedia.org/wiki/Schema:MediaWikiPingback
[] Manually evolve the Hive table to use new schema
[] Update [[ https://codesearch.wmcloud.org/analytics/?q=MediaWikiPingback&i=fosho&repos=analytics/reportupdater-queries | the queries in the analytics/reportupdater-queries repo ]]
[] Add entries to wgEventStreams in operations/mediwiki-config
** Since the Pingback instrument doesn't use EventLogging, we don't have to add entries to `$wgEventLoggingStreamNames` or `$wgEventLoggingSchemas`
[] Once the legacy stream's data is fully produced through EventGate, switch to using Refine job that uses schema repo instead of meta.wm.org
=== Links
1. [[ https://gerrit.wikimedia.org/g/mediawiki/core/+/af872aef1ab2a128ee46dcc03804950f04a83c16/includes/Pingback.php | Implementation in MediaWiki Core ]]
1. https://wikitech.wikimedia.org/wiki/Event_Platform/EventLogging_legacy