Replaces torch.norm with torch.linalg.norm for consistency

[fan-ziqi]

Description

Since torch.norm is deprecated and may be removed in a future PyTorch release (document here), Standardizes tensor norm calculations throughout the codebase by switching from torch.norm to torch.linalg.norm. This ensures compatibility with current PyTorch best practices and improves clarity for future maintenance.

Type of change

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

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

[fan-ziqi]

Fixed all incorrect replacements

[jtigue-bdai]

@Mayankm96 @kellyguo11 some tests are failing even though getting all green