fix(setup): steps 10 and 11 (#5987)

* fix(step10): count amount of wrong_events manually

* fix(step11): create index for better performance

cmd/setup/11/postgres/create_index.sql

@@ -0,0 +1,4 @@
+CREATE INDEX IF NOT EXISTS ca_fill_idx ON eventstore.events (
+    event_sequence DESC
+    , instance_id
+) WHERE created_at IS NULL; 

cmd/setup/11/postgres/drop_index.sql

@@ -0,0 +1 @@
+DROP INDEX IF EXISTS eventstore.ca_fill_idx;