Revert of [gn] Switch more linux32 bots to gn (patchset #3 id:40001 of https://codereview.chromium.org/2122933002/ )

Reason for revert:
Breaks test isolation on shared library bot.

Original issue's description:
> [gn] Switch more linux32 bots to gn
>
> This switches nosnap and shared library bots to gn.
>
> This also unsets external startup data if no snapshot is
> used.
>
> BUG=chromium:474921
> NOTRY=true
>
> Committed: https://crrev.com/ab4d8fc07d9d35e6fc129098f42aa0317a02244a
> Cr-Commit-Position: refs/heads/master@{#37546}

TBR=vogelheim@chromium.org,jochen@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:474921

Review-Url: https://codereview.chromium.org/2128493002
Cr-Commit-Position: refs/heads/master@{#37548}