Fixes ray initialization to correctly direct subprocess output

[ozhanozen]

Description

When running Ray directly from tuner.py, Ray is not correctly initialized within invoke_tuning_run(). The two problems associated with this are discussed in #3532. To solve them, this PR:

1. Removes ray_init() from util.get_gpu_node_resources(). Now, ray needs to be initialized before calling util.get_gpu_node_resources(). This change actually reverses Fixes the missing Ray initialization #3350, which was merged to add the missing initialization when using tuner.py, but it is safer to explicitly initialize Ray with the correct arguments outside of the util.get_gpu_node_resources().
2. Moves Ray initialization within invoke_tuning_run() to be before util.get_gpu_node_resources() so we explicitly initialize it before and do not raise an exception later.
3. Adds a warning when calling ray_init() if Ray was already initialized.

Fixes #3532

Type of change

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

Screenshots

Change 1:

Change 2:

Change 3:

Checklist

• I have read and understood the contribution guidelines
• 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

[garylvov]

LGTM thanks for catching this!