This is split from T288848: Make HTTP calls work within mediawiki on kubernetes .
Currently this functionality is enabled on group0 wikis, it just needs to be rolled out to remaining wikis, with a bit of monitoring of logs/potential user complaints.
// Temporary setting to stage the rollout of $wgLocalHTTPProxy (T288848) 'wmgUseLocalHTTPProxy' => [ 'default' => false, 'group0' => true, ],