Cleanup EarlyLibraryLoad from fieldtrial_testing_config.json.

R=cduvall@chromium.org

Bug: 1289680
Change-Id: I59b81c0a42d9cc5f8807422d0ec9fc672b38c340
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3412791


Auto-Submit: Francois Pierre Doray <fdoray@chromium.org>
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/main@{#962536}