fix(job_attachment)!: remove os_group field from Windows filesystem permission settings

[gahyusuh]

What was the problem/requirement? (What/Why)

The os_group field in the WindowsFileSystemPermissionSettings was identified as unnecessary and marked for removal to simplify the interface.

What was the solution? (How)

To keep backward compatibility, we planned 3-phase removal:

1. Make the file Optional (PR: fix(job_attachment)!: use username instead of group for Windows file permissions setting #196)
2. Update the dependent package to stop passing os_group when creating WindowsFileSystemPermissionSettings object. (PR: chore(deps): upgrade to openjd-sessions 0.7.* and deadline 0.40.* deadline-cloud-worker-agent#213)
3. Completely remove the field.

Steps 1 and 2 had been done. This PR is for Step 3.

Also, removed the PosixFileSystemPermissionSettings in the models.py. This whole class was moved to os_file_permissions.py, and we already fixed worker agent to import PosixFileSystemPermissionSettings from os_file_permission. (PR: aws-deadline/deadline-cloud-worker-agent#81)

What is the impact of this change?

We simplify the interface.

How was this change tested?

• Unit tests: hatch run lint && hatch run test
• Integ tests: hatch run integ:test
• Ran a quick E2E test to make sure that removing PosixFileSystemPermissionSettings in the models.py does not break anything, and job submission & worker's input syncing are working as usual.

Was this change documented?

Is this a breaking change?

This is breaking change for any package that still uses the os_group field in the WindowsFileSystemPermissionSettings class. The only place is was being used was deadline-cloud-worker-agent, and we have already done the Step 2 to remove that usage.

[ddneilson]

Thanks! I've updated the title from chore to fix -- that ensures that this breaking change shows up in the changelog at release. Chores don't get listed, and it's important that breaking changes get listed.

[gahyusuh]

Thank you @ddneilson for updating the title, I have fixed the commit message to match the title.