Merge branch 'ps/t7528-ssh-agent-uds-workaround'

Recent OpenSSH creates the Unix domain socket to communicate with
ssh-agent under $HOME instead of /tmp, which causes our test to
fail doe to overly long pathname in our test environment, which has
been worked around by using "ssh-agent -T".

* ps/t7528-ssh-agent-uds-workaround:
  t7528: work around ETOOMANY in OpenSSH 10.1 and newer