fix: maintenance index name, shared host read only view and badge polling

plugins/automations/migrations/mysql/0004_rename_maintenance_index.sql

@@ -0,0 +1,5 @@
+-- automations 0004: rename_maintenance_index
+-- Renames the maintenance index to the idx_ pattern every other index uses.
+
+CREATE UNIQUE INDEX `idx_automation_maintenance_host_owner` ON `p_automations_host_maintenance` (`user_id`, `host_id`);
+DROP INDEX `maintenance_host_owner` ON `p_automations_host_maintenance`;