Stable v2.9.72

• fix(install): don't leave the server without a resolver when disabling the stub
• fix(dns): stop PowerDNS's unresolvable security poll
• fix(install): quota mount option alone was taken as proof quota works
• fix(install): unbound cannot start without its DNSSEC trust anchor
• fix(ui): correct the backup server endpoint and stop the admin quota 404
• fix(stats): exclude our own test installs from the execution count
• fix(stats): count executed installs, not scanner fetches