Add metric name for MinVideoAndAudioBitRate.
Add metric name for MinVideoAndAudioBitRate.

It shouldn't be empty. As it was before it printed
  RESULT min_test_bitrate_no_allocation_strategy: = 80 kbps
Whereas now it prints
  RESULT min_test_bitrate_no_allocation_strategy: min_bitrate= 80 kbps

Bug: webrtc:7156
Change-Id: Ie86e3912d296d6d7bd6936d1709df9d2dc7fc143
Reviewed-on: https://webrtc-review.googlesource.com/38040
Reviewed-by: Patrik Höglund <b486136ee68458b09c92c86c39f451c87d6ef6a1@webrtc.org>
Reviewed-by: Henrik Andreassson <e468f06af92d21183a2a635f545ff5cefc8c8b65@webrtc.org>
Commit-Queue: Edward Lemur <d05609f027dc667cc37492b1dc1bdea5d60fa82a@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#21529}
TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc