PyFV3: Removing --no_legacy_namelist flag

[jjuyeonkim]

Description
This is a follow-up (clean-up) from PR NOAA-GFDL/NDSL#297.

It removes the flag --no_legacy_namelist flag from the github workflows.

How Has This Been Tested?
It passes CI

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• 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
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• Targeted model if this changed was triggered by a model need/shortcoming

[romanc]

🧹

[jjuyeonkim]

There seems to be an intermittent CI failure with the pyFV3 translate tests. It failed the first time in the merge queue, but passed when I reran. I'm noting this here. I'm going to try to merge one more time.

[romanc]

There seems to be an intermittent CI failure with the pyFV3 translate tests. It failed the first time in the merge queue, but passed when I reran. I'm noting this here. I'm going to try to merge one more time.

Yeah, we have seen this before. It usually goes away when re-runnig...