Reland of [gn] Switch more linux32 bots to gn (patchset #1 id:1 of https://codereview.chromium.org/2128493002/ )

Reason for revert:
Should be fixed after https://codereview.chromium.org/2123223002/

Original issue's description:
> 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
>
> Committed: https://crrev.com/a5fa2984257a50ee9440914c7d1a199f64a86194
> Cr-Commit-Position: refs/heads/master@{#37548}

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/2126843002
Cr-Commit-Position: refs/heads/master@{#37558}