Change public timelines to be filtered by current locale by default (#19291)

In the absence of an opt-in to multiple specific languages in the
preferences, it makes more sense to filter by the user's presumed
language only (interface language or `lang` override)

app/controllers/api/v1/timelines/public_controller.rb

@@ -35,6 +35,7 @@ class Api::V1::Timelines::PublicController < Api::BaseController
   def public_feed
     PublicFeed.new(
       current_account,
+      locale: content_locale,
       local: truthy_param?(:local),
       remote: truthy_param?(:remote),
       only_media: truthy_param?(:only_media)

app/controllers/api/v1/timelines/tag_controller.rb

@@ -36,6 +36,7 @@ class Api::V1::Timelines::TagController < Api::BaseController
     TagFeed.new(
       @tag,
       current_account,
+      locale: content_locale,
       any: params[:any],
       all: params[:all],
       none: params[:none],