Fix "before delete on" trigger on Scheduling Specification Conditions

If a "before" trigger returns `NULL`, the operation is cancelled, as per the Postgres Documentation (https://www.postgresql.org/docs/16/trigger-definition.html).

deployment/hasura/migrations/Aerie/13_before_delete_trigger_fix/down.sql

@@ -0,0 +1,12 @@
+create or replace function scheduler.increment_spec_revision_on_conditions_spec_delete()
+  returns trigger
+  security definer
+language plpgsql as $$
+begin
+  update scheduler.scheduling_specification
+  set revision = revision + 1
+  where id = new.specification_id;
+  return new;
+end;
+$$;
+call migrations.mark_migration_rolled_back('13');

deployment/hasura/migrations/Aerie/13_before_delete_trigger_fix/up.sql

@@ -0,0 +1,12 @@
+create or replace function scheduler.increment_spec_revision_on_conditions_spec_delete()
+  returns trigger
+  security definer
+language plpgsql as $$
+begin
+  update scheduler.scheduling_specification
+  set revision = revision + 1
+  where id = new.specification_id;
+  return old;
+end;
+$$;
+call migrations.mark_migration_applied('13');

deployment/postgres-init-db/sql/applied_migrations.sql

@@ -15,3 +15,4 @@ call migrations.mark_migration_applied('9');
 call migrations.mark_migration_applied('10');
 call migrations.mark_migration_applied('11');
 call migrations.mark_migration_applied('12');
+call migrations.mark_migration_applied('13');

deployment/postgres-init-db/sql/tables/scheduler/scheduling_specification/scheduling_specification_conditions.sql

@@ -59,7 +59,7 @@ begin
   update scheduler.scheduling_specification
   set revision = revision + 1
   where id = new.specification_id;
-  return new;
+  return old;
 end;
 $$;