x/build: Linux distribution too old on some builders

[cherrymui]

At least on some builders (e.g. linux-arm64-aws, linux-ppc64le-buildlet), it currently has Debian buster, which seems currently "oldstable". It seems still supported, but it causes apt-get update command to fail. This is inconvenient for gomote uses, also causes cmd/racebuild script to fail.

A workaround is apt-get --allow-releaseinfo-change update. But I'm not sure if it is a good idea for long term.

[gopherbot]

Change https://go.dev/cl/397475 mentions this issue: cmd/racebuild: work around old Linux distribution on builders

[cagedmantis]

Have all of these been updated to bullseye (or a current version of Ubuntu)?

[gopherbot]

Change https://go.dev/cl/421254 mentions this issue: cmd/racebuild: pass --allow-releaseinfo-change to apt-get update