This reverts commit 47b67c42.

Reason for revert: Bug in bot_update.py resource, breaks recipe roller.

Original change's description:
> Reland "bot_update recipe: Upload source manifest"
> 
> This reverts commit c3d1208d.
> 
> Also:
> * Instead of replacing "manifest", just add a new "source_manifest" 
> to the output JSON.  This allow transition without breakage.
> * Change the test api so test for recipe output changes.
> 
> The plan is to land this first, switch all downstream to "source_manifest",
> and then remove the original "manifest" key.
> 
> Bug: 772529,776299
> Change-Id: Iffb75f18046f8e4c058afe077872d4257b9dd754
> Recipe-Nontrivial-Roll: infra
> Recipe-Nontrivial-Roll: build_limited_scripts_slave
> Recipe-Nontrivial-Roll: skiabuildbot
> Recipe-Nontrivial-Roll: release_scripts
> Recipe-Nontrivial-Roll: skia
> Recipe-Nontrivial-Roll: skiabuildbot
> Recipe-Nontrivial-Roll: build
> Reviewed-on: https://chromium-review.googlesource.com/731378
> Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
> Commit-Queue: Ryan Tseng <hinoka@chromium.org>

TBR=iannucci@chromium.org,hinoka@chromium.org

Change-Id: I7a4ee904075e8b75b8a47f9ef0cd8a633af85a9c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 772529, 776299
Reviewed-on: https://chromium-review.googlesource.com/748312Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Commit-Queue: Ryan Tseng <hinoka@chromium.org>