update package fixture to module level for iface_loopback_action

[ZhaohuiS]

Description of PR

iface_loopback_action folder was new added in #5871.
It uses package level fixture which will run the conftest before sanity check.
In ports_configuration it did some remove vlan member or portchannel member operation, which will cause the following sanity check failure obviously.

Summary:
Fixes # (issue)

Type of change

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

Back port request

• 201911
• 202012
• 202205

Approach

What is the motivation for this PR?

Make sanity check run before conftest of iface loopback action.

How did you do it?

Use module level fixture instead.

How did you verify/test it?

Run iface_loopback_action/test_iface_loopback_action.py without skip-sanity option

Any platform specific information?

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

Documentation

[wangxin]

The pre-commit check detected issues in the files touched by this pull request.
The detected issues may be old or new. For new issues, please try to fix them.

For old issues, it is not mandatory to fix them because they were not caused by this change. It is unfair to blame
author of this pull request. But if you can take extra effort to fix the old issues as well, that would be great!

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/common/fixtures/duthost_utils.py:170:121: E501 line too long (121 > 120 characters)
tests/common/fixtures/duthost_utils.py:474:121: E501 line too long (122 > 120 characters)
tests/common/fixtures/duthost_utils.py:476:121: E501 line too long (126 > 120 characters)
tests/common/fixtures/duthost_utils.py:478:121: E501 line too long (128 > 120 characters)
tests/common/fixtures/duthost_utils.py:480:121: E501 line too long (146 > 120 characters)
tests/common/fixtures/duthost_utils.py:482:121: E501 line too long (126 > 120 characters)
tests/common/fixtures/duthost_utils.py:483:5: E722 do not use bare 'except'
tests/common/fixtures/duthost_utils.py:522:5: E722 do not use bare 'except'
tests/common/fixtures/duthost_utils.py:546:5: E722 do not use bare 'except'

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