Revert "[Speed Waterfall] Official benchmarks not longer need to run across all platforms."

This reverts commit 49cbd4e9bf6c5dd5d4f5347555f2f8e2f5e19399.

Reason for revert: This causes error "RuntimeError: Platform does not have a shard map at /usr/local/google/home/crouleau/chromium/chromium/src/tools/perf/core/shard_maps/android_arm64-builder-perf_map.json."
I will fix this and reland with PRESUBMIT support. (I assumed PRESUBMIT would cover this, but it didn't).

Original change's description:
> [Speed Waterfall] Official benchmarks not longer need to run across all platforms.
> 
> The current code has an assumption that every official benchmark must be scheduled
> on either pixel2 or linux platform. However, we are hoping to allow benchmarks
> to choose when platforms are the most important for them instead of having them
> run across all platforms by default.
> 
> Bug: 961830
> Change-Id: I26de896c921a85213a867e89ff137fce81959550
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610484
> Reviewed-by: John Chen <johnchen@chromium.org>
> Reviewed-by: John Budorick <jbudorick@chromium.org>
> Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#659293}

TBR=crouleau@chromium.org,johnchen@chromium.org,jbudorick@chromium.org

Change-Id: Ic4c6b34bbc0dc73484a670e5b1b39bd05849afd0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 961830
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610094
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659626}
1 file changed