Fixes MARL workflows for recording videos during training/inferencing

[Rishi-V]

Description

Fixing bug so that using training workflow on MARL workflow populates videos/train.
See #1595

Type of change

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

Screenshots

The first run was without the changes where we see videos/train empty. The second run is after the changes with videos/train successfully populated.

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• [N/A] I have made corresponding changes to the documentation
• My changes generate no new warnings
• [Sort of] I have added tests that prove my fix is effective or that my feature works; I have verified that it works on train.py for skrl and rl_games. I have not verified rsl_rl or sb3 as well have not verified play.py on any of the four. However I have implemented the changes on all of them as they all seem to follow the exact same structure.
• 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; Unsure if this fix is worth being labelled as a contributor, if so would be happy to be added to the contributors.md (full name is Rishi Veerapaneni).