autotest.py: changed 'prerequesites' to correct spelling

In a few places in autotest, the word 'prerequisites' was misspelled as 'prerequesites'. This is just a simple commit to fix that spelling.
autotest_jenkins.py: Fixed spelling of prerequisites

Same change as in autotest.py, just correcting the spelling of 'prerequisites' in a couple places from the original misspelled 'prerequesites'