test: bump timeout for test-libcrypt-util

Apparently this test is prone to time out on slower architectures, so
bump it from 30s to 120s.

See
https://buildd.debian.org/status/fetch.php?pkg=systemd&arch=mipsel&ver=247%7Erc2-2&stamp=1605303506&raw=0
https://buildd.debian.org/status/fetch.php?pkg=systemd&arch=sparc64&ver=247%7Erc2-2&stamp=1605294845&raw=0