autotest: remove pause after starting ArduPilot binary

Tools/autotest/pysim/util.py

@@ -601,8 +601,6 @@ def start_SITL(binary,
         rest = cmd[1:]
         child = pexpect.spawn(first, rest, logfile=pexpect_logfile, encoding=ENCODING, timeout=5)
         pexpect_autoclose(child)
-    # give time for parameters to properly setup
-    time.sleep(3)
     if gdb or lldb:
         # if we run GDB we do so in an xterm.  "Waiting for
         # connection" is never going to appear on xterm's output.