docker: fix already running httpd issue on distgit
    
    I was trying to hackishly fix this in 6ae31277, but it probably won't
    help, because `pidof httpd` is none.
    
        [root@distgit /]# pidof httpd
        [root@distgit /]# /usr/sbin/httpd -DFOREGROUND
        httpd (pid 35) already running
    
    The mentioned PID is of the following process
    
        /usr/libexec/git-core/git-daemon --base-path=/var/lib/dist-git/git \
            --export-all --user-path=public_git --syslog --inetd --verbose
    
    Which is started by our supervisord. The question is, do we really need
    it? I don't think so, since we can just remove it and the docker compose
    environment works just fine.
    
    Merges: #1098