Tools: reduce mavproxy memory usage on autotest

Tools/autotest/pysim/util.py

@@ -340,6 +340,7 @@ def start_MAVProxy_SITL(atype, aircraft=None, setup=False, master='tcp:127.0.0.1
         aircraft = 'test.%s' % atype
     cmd += ' --aircraft=%s' % aircraft
     cmd += ' ' + ' '.join(options)
+    cmd += ' --default-modules misc,terrain,relay,log,wp,rally,fence,param,arm,mode,rc,cmdlong,output'
     ret = pexpect.spawn(cmd, logfile=logfile, encoding=ENCODING, timeout=60)
     ret.delaybeforesend = 0
     pexpect_autoclose(ret)