Update CRUD sample to using built-in roles

[andreyaksenov]

Related dev. issue(s): tarantool/crud#415

Product: Tarantool, crud
Since: Tarantool 3.1, crud 1.5.0+
SME: @ DifferentialOrange

Details

Sample: https://github.com/tarantool/doc/tree/latest/doc/code_snippets/snippets/sharding/instances.enabled/sharded_cluster_crud

CRUD docs: https://github.com/tarantool/crud?tab=readme-ov-file#tarantool-3-roles