[JAX] Resolve test conflict in JAX helper tests

[emmanuel-ferdman]

Description

This small PR resolves a test method name conflict by renaming duplicated test_fp8_autocast_mxfp8_scaling methods to distinct names: test_fp8_autocast_mxfp8_current_scaling for Float8CurrentScaling tests and test_fp8_autocast_mxfp8_block_scaling for MXFP8BlockScaling tests.

Fixes # (issue)

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

• Resolve test conflict in JAX helper tests

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• 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
• New and existing unit tests pass locally with my changes