Remove unused voe_stress_test.cc

BUG=webrtc:4690

Review-Url: https://codereview.webrtc.org/2681153003
Cr-Original-Commit-Position: refs/heads/master@{#16513}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 0289364abc38c2bf8299edb434529af23d44e9dc
7 files changed