Small tweaks to Tile Benchmark test

* tag the module as 'tests' so the apk gets includes in test build
* merge the instrumentation into TileBenchmark app and eliminate
  the test apk entirely
* changed the default test suite to 'alexa25_2011' which is a suite
  of pages based on top 25 news sites from alexa, includes primarily
  english sites, and 3 CJK sites

Change-Id: Icd40a70b560bfd7c521adf8ad4b1068483698103