Fix implicit import in test_monitoring.py

[SubbaraoGarlapati]

test.support.import_helper in Lib/test/test_monitoring.py is not actually imported in the file, relying on another import to import it. As discussed in the previous pull request, this would be fine if importing test.support itself would import test.support.import_helper but that's not the case.

% python -c "import test.support; test.support.import_helper"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import test.support; test.support.import_helper
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'test.support' has no attribute 'import_helper'

[colesbury]

Thanks!

[miss-islington-app]

Thanks @SubbaraoGarlapati for the PR, and @colesbury for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-141920 is a backport of this pull request to the 3.14 branch.