Update timedtext unittest

unit test changes to match timedtext parser, which changed to
match the existing consumer. Mismatched use of parcel::write() vs writeByteArray()

Bug: 150915309
Test: atest TimedTextUnitTest, cts
Test: atest CtsMediaTestCases:android.media.cts.MediaPlayerTest#testChangeTimedTextTrack
Change-Id: I91de138f5a177b394e86bb31a5ec294249159ebe