Make tempest-multinode-full py2 job on py2

tempest-multinode-full is python2 version
of mutlinode testing for stable branches and
supposed to run on python 2 but it was left during
- I75868d5c9b6630fe78958ff89e58a0aced09a6b3

Change-Id: Ibec72b578424cb278006ac810bdd0359ec23de3f
1 file changed