Loosen availabilityWindowOverride test tolerance.
Loosen availabilityWindowOverride test tolerance.

The HLS availabilityWindowOverride test has failed multiple times on
our automatic nightly tests. That is likely due to the equality check
based on the current clock time.
This loosens the tolerance on the check, so it won't fail.

Change-Id: I9ac11bab06d156db7956088fa11fd7ba8c52704b

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