Convert gn_unittests to run exclusively on Swarming

0 configs already ran on Swarming
3 used to run locally and were converted:
- chromium.linux.json: Linux Tests
- chromium.linux.json: Linux Tests (dbg)(1)
- chromium.linux.json: Linux Tests (dbg)(1)(32)

Ran:
  ./manage.py --convert gn_unittests

BUG=98637

Review URL: https://codereview.chromium.org/1214533005

Cr-Original-Commit-Position: refs/heads/master@{#336929}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: ddcc0a4109ccb62eeac7bd9eaf0efbc22412d8f8
2 files changed
tree: 6e137ebb4bd8da18e725d3d0a6b275e9ede41c10
  1. tools/