[UPM] Adding M4 setup to fieldtrial_testing_config.json

Change-Id: I84b524fec6b75d7e412b876d5471d62883920472
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5425024


Commit-Queue: Viktor Semeniuk <vsemeniuk@google.com>
Reviewed-by: Anna Tsvirchkova <atsvirchkova@google.com>
Cr-Commit-Position: refs/heads/main@{#1283068}