PostgreSQL DDL for constraints backed by indexes incorrectly includes the index definition

### Description

The DDL generated for a table with a constraint of the form `CONSTRAINT foo_ck EXCLUDE USING btree (id WITH =, bar WITH =) WHERE ((baz = 2)) DEFERRABLE INITIALLY DEFERRED` is incorrectly adding an index statement `CREATE INDEX foo_ck ON public.t_foo USING btree (id, bar) WHERE (baz = 2)`. That index is an implementation detail and will be created by PostgreSQL as part of the constraint creation. Thus the copied DDL can not be directly executed without further editing of that DDL.

This is similar to https://github.com/dbeaver/dbeaver/issues/7443 but applies to non-unique indexes.

### DBeaver Version

25.2.0 Community

### Operating System

NixOS 25.05

### Database and driver

PostgreSQL 14.19
PostgreSQL JDBC driver 42.7.2

### Steps to reproduce

1. create table with constraint `CONSTRAINT foo_ck EXCLUDE USING btree (id WITH =, bar WITH =) WHERE ((baz = 2)) DEFERRABLE INITIALLY DEFERRED`
2. right click on table and select the "Generate SQL --> DDL" menu option

### Additional context

_No response_