Testing: Call SetMultiSamples(0) from tests

...so anti-aliasing doesn't cause the image comparison to fail by a
slim margin.

These tests pass on the "mug.neocisinc" dashboard client with this
change applied.

Change-Id: I91c640e3958e3c034e3e7674af4f76d63fcfa6aa
Merge topic 'prevent-anti-aliasing-in-some-tests' into master

c3e52096 Testing: Call SetMultiSamples(0) from tests