Limit transcoding size workaround to windows

Test: Connect android to windows through usbc.
      Enable mtp, then enable the transcoding option.
      Copy H265 video from the camera folder to windows' desktop.
      Transcoded H264 video plays correctly in WMPcorrectly.

Bug: 184117074
Bug: 190422448
Change-Id: I17264f0ee3e742315569d4c50817b1da7f3f2eb4