fix(clickhouse): simplify obsolete index migration

Author: carderne

internal-packages/clickhouse/schema/042_reduce_task_events_v2_storage_overhead.sql

@@ -6,11 +6,6 @@ ALTER TABLE trigger_dev.task_events_v2
     DROP INDEX IF EXISTS idx_attributes_text_search,
     DROP INDEX IF EXISTS idx_attributes_text,
     DROP INDEX IF EXISTS idx_message_text_search,
-    DROP INDEX IF EXISTS message_text_search
-SETTINGS mutations_sync = 2, alter_sync = 2;
+    DROP INDEX IF EXISTS message_text_search;
 
 -- +goose Down
-
--- Restoring these indexes safely requires selecting the appropriate index
--- definitions and materializing them in a new forward migration.
-SELECT throwIf(1, 'This migration cannot be rolled back automatically');