Flip Linux x64, linux_chromium_archive_rel_ng bots to GN
This patch adds MB support for the new 'linux_chromium_archive_rel_ng'
bot and flips it and the 'Linux x64' waterfall bot to GN.
This bot should replace the 'linux_chromium_clobber_rel_ng' bot ASAP
since that bot is doing a GYP build of 'chromium_builder_tests',
which isn't that interesting, and the supposed builder that that bot
is mirroring, 'Linux Builder (clobber)' on the chromium.fyi waterfall,
doesn't actually exist.