PSA: Remove workaround for picture id/tl0 index jumps in VP9.

[Philip Eliasson]

Hello!

As the new jitter buffer was developed we discovered that the picture id/tl0 index was re-randomized every time the encoder was reconfigured. To make the new jitter buffer compatible with older versions of chrome a workaround was introduced on the receiving side to detect and correct the jumps.

This workaround will be removed in M62, CL here: https://codereview.chromium.org/2969043002/.