SoundPoolTest: fix volume. Volume is out of bounds for some of the tests; an integer value of 10 and 20 is used - it should be a float value between 0.f and 1.f. This is bad example code. Test: SoundPoolOggTest, listen for sounds. Bug: 23978255 Change-Id: I2bbd46f266911752041a17f4c0b153914ea1cce0