Revert "[SPv175] Enable SlimmingPaintV175 by default"

This reverts commit 0a9a5c311a1d3a298f952e495510bd6fe3faa2f6.

Reason for revert: We decided to delay the launch of SlimmingPaintV175
to M67, so that we have more time to fix the regressions.

The revert CL is slightly modified so that later enabling/disabling of
SlimmingPaintV175 by default can just change one line in
content/public/common/content_features.cc (learnt from
RootLayerScrolling crrev/c/929662).

Original change's description:
> [SPv175] Enable SlimmingPaintV175 by default
>
> SlimmingPaintV175 enables raster invalidation and paint chunks based
> on paint properties. See crbug.com/771643.
>
> Bug: 771643
> Change-Id: I5fdbcabc7ca0f2fa8e69ae0fbf5a0077bba46cfe
> Reviewed-on: https://chromium-review.googlesource.com/923572
> Reviewed-by: Antoine Labour <piman@chromium.org>
> Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#537454}

TBR=dgozman@chromium.org,wangxianzhu@chromium.org,chrishtr@chromium.org,piman@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 771643
Change-Id: I04177ada5d6b133fe47c0e0dbff42b6989f099ba
Reviewed-on: https://chromium-review.googlesource.com/938562
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539401}
2 files changed