[CfT] Tweak linux-arm64-rel-cft builder config

Bug: chromium:1440652
Change-Id: I84811cb1352885551326d6abd0fcb38f9cdceddf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4582054


Commit-Queue: Wanda Mora <morawand@google.com>
Reviewed-by: Wanda Mora <morawand@google.com>
Cr-Commit-Position: refs/heads/main@{#1152636}