Revert of [build] Use MSVS 2015 by default. (patchset #4 id:60001 of https://codereview.chromium.org/1886983002/ )

Reason for revert:
Introduced flaky crashes on win debug.

Original issue's description:
> [build] Use MSVS 2015 by default.
>
> BUG=chromium:603131
> LOG=y
>
> Committed: https://crrev.com/e51e8b4ad77008ec7f88c144853e01001dbea900
> Cr-Commit-Position: refs/heads/master@{#35487}

TBR=jochen@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:603131

Review URL: https://codereview.chromium.org/1890873002

Cr-Commit-Position: refs/heads/master@{#35498}