test: Fix pytest that failed since commit 3dd89ca

Additional mocker patch added to test 'test_check_if_using_old_version_yum_works' to make it pass again.

fixes: https://github.com/aws/efs-utils/issues/179

Issue #, if available: https://github.com/aws/efs-utils/issues/179

Description of changes: The CircleCI project status is red (https://circleci.com/gh/aws/efs-utils), because all Python tests in the public circleci pipeline are in a failed state:

Reason is the assertion in test_check_if_using_old_version.py: https://github.com/aws/efs-utils/blob/d5a0812c94f39336162381c6afb5d4eec7b418a0/test/watchdog_test/test_check_if_using_old_version.py#L39-L45

This code was introduced in commit https://github.com/aws/efs-utils/commit/3dd89caef058c744a419b6839416d726cdc5ab54

It uses EFSUtilsVersionChecker.check_if_using_old_version (https://github.com/aws/efs-utils/blob/master/src/watchdog/__init__.py#L382),

if EFSUtilsVersionChecker.SHOULD_CHECK_AMZN_REPOS: in line 389 only checks for new versions in the repos if the test runs on AL. For all others, we run into the try statement in 407 and 412 (https://github.com/aws/efs-utils/blob/master/src/watchdog/__init__.py#L412) returns a warning: https://github.com/aws/efs-utils/blob/d5a0812c94f39336162381c6afb5d4eec7b418a0/src/watchdog/__init__.py#L320-L328

that differs from the warning returned if its AL: https://github.com/aws/efs-utils/blob/d5a0812c94f39336162381c6afb5d4eec7b418a0/src/watchdog/__init__.py#L309-L317

The circleci based test run in python:3.y.z container images and will therefore always trigger the github version check.

By adding an additional mocker patch to enforce the AL behavior like this:

    mocker.patch(
        "watchdog.EFSUtilsVersionChecker.SHOULD_CHECK_AMZN_REPOS",
        return_value=True,
    )

after https://github.com/aws/efs-utils/blob/d5a0812c94f39336162381c6afb5d4eec7b418a0/test/watchdog_test/test_check_if_using_old_version.py#L28-L38

The actual python based unittests go back to green based on local tests (circleci local execute python3_9, circleci local execute python3_8, circleci local execute python3_7, circleci local execute python3_6, circleci local execute python3_5, circleci local execute python3_4), test/watchdog_test/test_check_if_using_old_version.py::test_check_if_using_old_version_yum_works PASSED on all versions, no errors anymore:

pytest
============================= test session starts ==============================
platform linux -- Python 3.9.13, pytest-4.6.7, py-1.10.0, pluggy-0.13.0 -- /root/efs-utils-virtualenv/bin/python
[...]
Required test coverage of 80% reached. Total coverage: 84.89%
========================= 557 passed in 18.06 seconds ==========================

pytest
============================= test session starts ==============================
platform linux -- Python 3.8.13, pytest-4.6.7, py-1.10.0, pluggy-0.13.0 -- /root/efs-utils-virtualenv/bin/python
[...]
Required test coverage of 80% reached. Total coverage: 84.89%
========================= 557 passed in 19.16 seconds ==========================

pytest
============================= test session starts ==============================
platform linux -- Python 3.7.13, pytest-4.6.7, py-1.10.0, pluggy-0.13.0 -- /root/efs-utils-virtualenv/bin/python
[...]
Required test coverage of 80% reached. Total coverage: 84.81%
========================= 557 passed in 17.75 seconds ==========================

pytest
============================= test session starts ==============================
platform linux -- Python 3.6.15, pytest-4.6.7, py-1.10.0, pluggy-0.13.0 -- /root/efs-utils-virtualenv/bin/python
[...]
Required test coverage of 80% reached. Total coverage: 84.81%
==================== 555 passed, 2 skipped in 16.96 seconds ====================

pytest
============================= test session starts ==============================
platform linux -- Python 3.5.10, pytest-4.6.7, py-1.10.0, pluggy-0.13.0 -- /root/efs-utils-virtualenv/bin/python
[...]
Required test coverage of 80% reached. Total coverage: 84.67%
==================== 554 passed, 3 skipped in 16.08 seconds ====================

pytest
============================= test session starts ==============================
platform linux -- Python 3.4.10, pytest-4.6.7, py-1.10.0, pluggy-0.13.0 -- /root/efs-utils-virtualenv/bin/python
[...]
Required test coverage of 80% reached. Total coverage: 84.43%
==================== 553 passed, 4 skipped in 17.80 seconds ====================

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aws / efs-utils

test: Fix pytest that failed since commit 3dd89ca #180