Add a fix for redefinition-while-unused

[charliermarsh]

Summary

This PR enables Ruff to remove redefined imports, as in:

import os
import os

print(os)

Previously, Ruff would flag F811 on the second import os, but couldn't fix it.

For now, this fix is marked as safe, but only available in preview.

Closes #3477.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+0 -0 violations, +4 -0 fixes in 1 projects; 42 projects unchanged)

aws/aws-sam-cli (+0 -0 violations, +4 -0 fixes)

ruff check --no-cache --exit-zero --preview

- tests/unit/commands/deploy/test_deploy_context.py:10:47: F811 Redefinition of unused `DeployFailedError` from line 8
+ tests/unit/commands/deploy/test_deploy_context.py:10:47: F811 [*] Redefinition of unused `DeployFailedError` from line 8
- tests/unit/local/docker/test_lambda_image.py:8:27: F811 Redefinition of unused `parameterized` from line 5
+ tests/unit/local/docker/test_lambda_image.py:8:27: F811 [*] Redefinition of unused `parameterized` from line 5

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
F811	4	0	0	4	0

[zanieb]

I think it can be safe if we merge #9418?

Probably? Seems safer to start this way.

[charliermarsh]

@zanieb - I'm not sure how to justify or explain that the fix is unsafe though, now that we removed branching. It should always be safe?

[zanieb]

@charliermarsh I guess so! I can't think of a case. We could gate the fix with preview for now?