Fix setting incorrect device in env_cfg

[amrmousa144]

Description

This pull request fixes the issue where the device (CPU or CUDA) is not set correctly when using the --device argument in Hydra-configured scripts like rsl_rl/train.py and skrl/train.py. The bug caused the scripts to always default to cuda:0, even when cpu or a specific CUDA device (e.g., cuda:1) was selected.

The fix adds the following line to ensure that the selected device is properly set in env_cfg before initializing the environment with gym.make():

env_cfg.sim.device = args_cli.device

Fixes # (issue)

[Bug Report] Incorrect device selection with Hydra configurations #1012

Type of change

• Bug fix (non-breaking change which fixes an issue)

Screenshots

Before:

• skrl/train, when running the script with --device cpu, it defaults to cuda:0.
• rsl_rl/train.py, the script freezes at [INFO]: Starting the simulation. This may take a few seconds. Please wait....
  After:
• Both scripts run correctly on the specified device (e.g., cpu or cuda:1) without defaulting to cuda:0 or freezing.

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there