Add a fieldtrial testing entry for DesktopAndroidLinkCapturing.

This CL was created on behalf of sinansahin.
Please review the CL and approve it if it looks good.
Contact the listed reviewers if you have any questions.

Change-Id: I9821d5c018faa1ad8eeb94de9660e729977751b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7685410
Auto-Submit: Chrome Metrics Config Manager <chrome-metrics-config-manager-server@google.com>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Luc Nguyen <lucnguyen@google.com>
Commit-Queue: Sinan Sahin <sinansahin@google.com>
Cr-Commit-Position: refs/heads/main@{#1603721}
NOKEYCHECK=True
GitOrigin-RevId: 4ab32cee4c292f2408aba1aeb61935ae9662c0a2