test: remove obsolete tee to global config

We use to modify the global sshd but we haven't done that for a few years. We
still did have this `tee` to allow password logins that we don't need anymore.
Remove this single instance of a `sudo`.

Author: carlosmn

script/travisbuild

@@ -74,7 +74,6 @@ export GITTEST_REMOTE_SSH_PUBKEY="$HOME/.ssh/id_rsa.pub"
 export GITTEST_REMOTE_SSH_PASSPHRASE=""
 export GITTEST_REMOTE_REPO_PATH="$HOME/_temp/test.git"
 
-echo 'PasswordAuthentication yes' | sudo tee -a /etc/sshd_config
 eval $(ssh-agent)
 ssh-add $GITTEST_REMOTE_SSH_KEY