output_processor/postgres: Fix out of range for hostid

Change the field type of `hostid` as part of `TargetInfo` from `Int` to
Bigint to prevent some ids from exceeding the maximum value.

wa/commands/postgres_schemas/postgres_schema_update_v1.5.sql

@@ -0,0 +1 @@
+ALTER TABLE targets ALTER hostid TYPE BIGINT;