This reverts commit 9311ef18.

Reason for revert:
Notice small regression in some clips.
Will revisit in another change.

Original change's description:
> Speed >=5 real-time: add TM intra mode for high_source_sad.
> 
> Small/neutral change in metrics or speed for ytlive.
> Some improvement in quality on frames with big content change.
> 
> Change-Id: Ib3b0703a5f28ea6710e90324436e27598ab7384d

TBR=marpan@google.com,builds@webmproject.org,jianj@google.com

Change-Id: I9d8ec5195bb05ddf329d325699355185affb9b13
No-Presubmit: true
No-Tree-Checks: true
No-Try: true