Random unittest faillure in test_file_is_draft_areas_limit_reached (take 2)

This is a follow-up from MDL-75231 as a second attempt to fix the "test_file_is_draft_areas_limit_reached" random failure.

The MDL above managed to reduce the number of failures however it's still happens every now and then specially on Oracle, for example this build.

Console output

1) core\filelib_test::test_file_is_draft_areas_limit_reached

Failed asserting that false is true.

/var/www/html/lib/tests/filelib_test.php:1884

/var/www/html/lib/phpunit/classes/advanced_testcase.php:94