test: Fix edge case in player integration test
test: Fix edge case in player integration test

If bufferBehind is set to 10, then having 10 seconds buffered behind
is fine.  It doesn't need to be strictly less than 10.

This test was previously failing only on Xbox One.

Change-Id: I6487e724753412614840b42eadfcd5edd71cc7bd

tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player