Reland of Deflake ChangingNetworkRoute test.
Reland of Deflake ChangingNetworkRoute test.

NOTRY=true
BUG=webrtc:6551

Review-Url: https://codereview.webrtc.org/2451553004
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#14766}

TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc