Fix: correct output scale compute

[Giuseppe5]

Reason for this PR

There is a bug when computing output scale factor, when the input scale is quantized per-row and the weights are quantized per channel

Changes Made in this PR

Resolves the issue by skipping scale factor computation in this case. This means that we cannot have a properly formed quant tensor with this quantization strategy.
In theory, if I am not hallucinating, the math would results in a per-element scale factor, but we need to decide whether it's worth keeping track of this since any operation with such QuantTensor would results in dequantize.

Testing Summary

None

Risk Highlight

NA

Checklist

• Code comments added to any hard-to-understand areas, if applicable.
• Changes generate no new warnings.
• Updated any relevant tests, if applicable.
• No conflicts with destination dev branch.
• I reviewed my own code changes.
• Initial CI/CD passing.
• 1+ reviews given, and any review issues addressed and approved.
• Post-review full CI/CD passing.