[Omnibox] Match fieldtrial_config for perf experiment to launch candidate

Bug: 1430541
Change-Id: I9213a73689097c4690a56051f894cd15a159a11d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4789433


Commit-Queue: Tomasz Wiszkowski <ender@google.com>
Commit-Queue: Patrick Noland <pnoland@chromium.org>
Reviewed-by: Tomasz Wiszkowski <ender@google.com>
Cr-Commit-Position: refs/heads/main@{#1184831}