Fix deleted pinned posts potentially counting towards the pinned posts limit (#19005)

Fixes #18938

app/controllers/api/v1/statuses_controller.rb

@@ -77,6 +77,7 @@ class Api::V1::StatusesController < Api::BaseController
     authorize @status, :destroy?
 
     @status.discard
+    StatusPin.find_by(status: @status)&.destroy
     @status.account.statuses_count = @status.account.statuses_count - 1
     json = render_to_body json: @status, serializer: REST::StatusSerializer, source_requested: true
 

app/services/remove_status_service.rb

@@ -21,6 +21,8 @@ class RemoveStatusService < BaseService
     with_lock("distribute:#{@status.id}") do
       @status.discard
 
+      StatusPin.find_by(status: @status)&.destroy
+
       remove_from_self if @account.local?
       remove_from_followers
       remove_from_lists