Add media_constrained_network_perf to PYAUTO_TESTS.
Add media_constrained_network_perf to PYAUTO_TESTS.

As titled, introduces the a new media constrained network perf test
into the PYAUTO_TESTS file. Also fixes incorrect flags on pyauto_media.

BUG=106257, 106260
TEST=Ran local Buildbot, manual verification.

Review URL: http://codereview.chromium.org/8961023

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@115247 0039d316-1c4b-4281-b951-d872f2087c98

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