Improve test_assign_groups_guess

[juliamagan]

Description

After the research done in #3776, we could see that test_assign_groups_guess is stable. However, it takes 21 minutes to finish the test execution. We need to reduce this time.

In addition, after the research done in #3876, we saw that we could improve the test by checking the following logs:

• Worker

2023/02/01 13:40:28 wazuh-remoted[1718] manager.c:556 at assign_group_to_agent_worker(): DEBUG: Sending message to master node: '{"daemon_name":"remoted","message":{"command":"assigngroup","parameters":{"agent":"060","md5":"x"}}}'
2023/02/01 13:40:28 wazuh-remoted[1718] manager.c:560 at assign_group_to_agent_worker(): DEBUG: Message received from master node: '{"error":0,"message":"ok","data":{"group":"default"}}'
2023/02/01 13:40:28 wazuh-remoted[1718] manager.c:1598 at wait_for_msgs(): DEBUG: Sending file 'default/merged.mg' to agent '060'.
2023/02/01 13:40:28 wazuh-remoted[1718] manager.c:1614 at wait_for_msgs(): DEBUG: End sending file 'default/merged.mg' to agent '060'.

• Master

2023/02/01 13:40:28 wazuh-remoted[1877] manager.c:508 at assign_group_to_agent(): DEBUG: Agent '060' with file 'merged.mg' MD5 'x'
2023/02/01 13:40:28 wazuh-remoted[1877] manager.c:527 at assign_group_to_agent(): DEBUG: Group assigned: 'default'