Enable low_cpu_mem_usage for mxfp/nvfp

[Kaihui-intel]

Description

#1127

Qwen3-32B nvfp4 enable/disable low_cpu_mem_usage
'peak_ram': 10.35GB, 'peak_vram': 60.75GB
'peak_ram': 30.35GB, 'peak_vram': 60.75GB

Type of Change

• Bug fix
• New feature
• Documentation update
• Performance improvement
• Code refactoring
• Other (please specify):

Related Issues

Fixes or relates to #

Checklist Before Submitting

• My code has been tested locally.
• Documentation has been updated as needed.
• New or updated tests are included where applicable.

[Copilot]

Pull request overview

Removes a guard that previously disabled immediate_saving for non-integer quantization types, likely to allow memory-saving flows for additional quantization formats.

Changes:

• Removed the runtime check that forced immediate_saving=False when data_type wasn’t integer-based.