tests: re-set the second memory test limit to 10MB for Travis
tests: re-set the second memory test limit to 10MB for Travis

Travis still obtain more than 5MB of difference on that test sometimes.
I hesitated between:
  1. raising up the sleeping time after GC and check if that changes
     something
  2. remove memory tests from being performed by travis
  3. raise up the limit to what it was before (10MB)

For now, I chose the third.

canalplus/rx-player,canalplus/rx-player,canalplus/rx-player,canalplus/rx-player,canalplus/rx-player