Remove old fix in ovpn-client

The fix to mark an interface as "up" and indicate its MTU was
useful for machines with a single client, because OpenVPN would fail
to configure them this way in OpenVPN 2.3. It has been fixed in 2.4
so the fix has been removed.

/reviewed-on nexedi/re6stnet!14

re6st/ovpn-client

 #!/usr/bin/python2 -S
-import os, sys
-
-script_type = os.environ['script_type']
-if script_type == 'up':
-    # OpenVPN unsets PATH before calling hooks
-    # which is equivalent to set /bin:/usr/bin
-    os.environ['PATH'] = '/bin:/sbin:/usr/bin:/usr/sbin'
-    os.execlp('ip', 'ip', 'link', 'set', os.environ['dev'], 'up',
-              'mtu', os.environ['tun_mtu'])
-
-if script_type == 'route-up':
-    import time
-    os.write(int(sys.argv[1]), repr((os.environ['common_name'], time.time(),
+import os, sys, time
+os.write(int(sys.argv[1]), repr((os.environ['common_name'], time.time(),
          int(os.environ['tls_serial_0']), os.environ['OPENVPN_external_ip'])))

re6st/plib.py

@@ -13,7 +13,6 @@ def openvpn(iface, encrypt, *args, **kw):
         '--persist-tun',
         '--persist-key',
         '--script-security', '2',
-        '--up', ovpn_client,
         #'--user', 'nobody', '--group', 'nogroup',
         ] + list(args)
     if ovpn_log: