test: create /run/sshd in TEST-74-AUX-UTILS

test: create /run/sshd in TEST-74-AUX-UTILS

12264s [ 4819.948632] sshd[1365]: fatal: Missing privilege separation directory: /run/sshd
12264s [ 4819.952120] testsuite-74.sh[1362]: kex_exchange_identification: read: Connection reset by peer
12264s [ 4819.952120] testsuite-74.sh[1362]: Connection reset by /run/ssh-unix-local/socket port 0

https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-upstream-systemd-ci-systemd-ci/jammy/amd64/s/systemd-upstream/20240113_093341_50fc7@/log.gz

We copy binaries manually so some setups are missing, create the directory
as needed