[Instrumented libraries] Switch default release to Focal

This should be a no-op on the bots since they manually specify
`instrumented_libraries_release`.  This change is mainly for gLinux,
where devs are having issues using the Xenial instrumented libraries
due to having different versions of dependencies (eg. libnettle.so.6).

R=thestig

Change-Id: Ic3aa74da1034c7c6b2826a7acb73a57bd3bcf393
Bug: 1260217, 1334390
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4074160
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1079527}
NOKEYCHECK=True
GitOrigin-RevId: a9feccefae2bdbe891fcee1d7f3783d91f43cba6
1 file changed