[Release][APT] Skip arm64 Ubuntu 21.04 verification

[asfimport]

qemu-user-static in Ubuntu 20.04 has a crash bug for it.

Reporter: Kouhei Sutou / @kou
Assignee: Kouhei Sutou / @kou

PRs and other links:

• GitHub Pull Request #11516

_{Note: This issue was originally created as ARROW-14433. Please see the migration documentation for further details.}

[asfimport]

Krisztian Szucs / @kszucs:
Issue resolved by pull request 11516
#11516