[CfT] Enable arm64 gclient config for linux-arm64-rel-cft builder

Bug: chromium:1440652
Change-Id: I2f41d9364ee8051ec19540aad2d1e0b7c5474f7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4543161


Reviewed-by: Thiago Perrotta <tperrotta@chromium.org>
Commit-Queue: Wanda Mora <morawand@google.com>
Auto-Submit: Mathias Bynens <mathias@chromium.org>
Reviewed-by: Wanda Mora <morawand@google.com>
Cr-Commit-Position: refs/heads/main@{#1145443}