Enable Py3 for test_lag_member

[saiarcot895]

Description of PR

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

PR #14001 moved the lag_test PTF script into the Python 3 folder, but PR #14031 missed updating this test.

How did you do it?

Update this test to reflect that the lag_test script should be run under Python 3.

How did you verify/test it?

Tested it on KVM after removing the mark to skip this test case on KVM and skipping the ARP checks.

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/pc/test_lag_member.py:349:27: F811 redefinition of unused 'copy_acstests_directory' from line 13
tests/pc/test_lag_member.py:349:52: F811 redefinition of unused 'copy_ptftests_directory' from line 13

flake8...............................................(no files to check)Skipped
check conditional mark sort..........................(no files to check)Skipped

To run the pre-commit checks locally, you can follow below steps:

1. Ensure that default python is python3. In sonic-mgmt docker container, default python is python2. You can run
   the check by activating the python3 virtual environment in sonic-mgmt docker container or outside of sonic-mgmt
   docker container.
2. Ensure that the pre-commit package is installed:

sudo pip install pre-commit

3. Go to repository root folder
4. Install the pre-commit hooks:

pre-commit install

5. Use pre-commit to check staged file:

pre-commit

6. Alternatively, you can check committed files using:

pre-commit run --from-ref <commit_id> --to-ref <commit_id>

[yaqiangz]

LGTM