Convert midi_unittests to run exclusively on Swarming

Convert midi_unittests to run exclusively on Swarming

13 configs already ran on Swarming
16 used to run locally and were converted:
- chromium.chromiumos.json: Linux ChromiumOS Ozone Tests (1)
- chromium.chromiumos.json: Linux ChromiumOS Tests (1)
- chromium.chromiumos.json: Linux ChromiumOS Tests (dbg)(1)
- chromium.fyi.json: CrWinAsan tester
- chromium.fyi.json: CrWinAsan(dll) tester
- chromium.fyi.json: Linux Trusty
- chromium.fyi.json: Linux Trusty (dbg)
- chromium.linux.json: Cast Linux
- chromium.memory.fyi.json: Linux ChromeOS MSan Tests
- chromium.memory.fyi.json: Linux MSan Tests
- chromium.memory.fyi.json: Linux TSan Tests
- chromium.memory.json: Linux ASan LSan Tests (1)
- chromium.memory.json: Linux Chromium OS ASan LSan Tests (1)
- chromium.memory.json: Mac ASan 64 Tests (1)
- chromium.webkit.json: Linux ChromiumOS Tests (1)
- chromium.webkit.json: Linux ChromiumOS Tests (dbg)(1)

Ran:
  ./manage.py --convert midi_unittests

TBR=dpranke@chromium.org
BUG=98637

Review URL: https://codereview.chromium.org/1212893002

Cr-Commit-Position: refs/heads/master@{#336377}