Revert "use reboot_ec cold by default"

This reverts commit bb6cc7c3281c8e3e946df93a20b1049fa409b3e3.

Reason for revert: crbug.com/1142910

Original change's description:
> use reboot_ec cold by default
>
> BUG=b/169461036
> TEST=ran REBOOT_CMD on DUT, confirmed that it rebooted, ran repair on lab DUT locally.
>
> Change-Id: I70f9ab44f9997261c0e44a29a56c8002f489622b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2427054
> Reviewed-by: Garry Wang <xianuowang@chromium.org>
> Reviewed-by: Otabek Kasimov <otabek@google.com>
> Tested-by: Gregory Nisbet <gregorynisbet@google.com>
> Commit-Queue: Gregory Nisbet <gregorynisbet@google.com>

Bug: b/169461036
Change-Id: Ib648b3f5efd65c71af9a4f8cd7ac983e7a356977
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2587260
Reviewed-by: Gregory Nisbet <gregorynisbet@google.com>
Reviewed-by: Otabek Kasimov <otabek@google.com>
Reviewed-by: Garry Wang <xianuowang@chromium.org>
Tested-by: Gregory Nisbet <gregorynisbet@google.com>
Commit-Queue: Gregory Nisbet <gregorynisbet@google.com>
diff --git a/server/control_segments/reset b/server/control_segments/reset
index 985f2ad..e54550f 100644
--- a/server/control_segments/reset
+++ b/server/control_segments/reset
@@ -17,15 +17,6 @@
 labels_list = [l.strip() for l in job_labels.split(',') if l]
 
 
-# try to reboot using ectool. If ectool fails, fall back to reboot and
-# reboot -f.
-REBOOT_CMD = '''
-sync& sleep 5;
-ectool reboot_ec cold;
-reboot& sleep 10;
-reboot -f
-'''
-
 def reset(machine):
     print('Starting to reset host %s' % machine)
     try:
@@ -35,7 +26,7 @@
         with metrics.SecondsTimer(DURATION_METRIC,
                                   fields={'dut_host_name': hostname}):
             # Assume cleanup always runs first.
-            target.cleanup(reboot_cmd=REBOOT_CMD)
+            target.cleanup()
             provision.Cleanup.run_task_actions(job, target, labels_list)
 
             target.verify()
diff --git a/server/hosts/cros_host.py b/server/hosts/cros_host.py
index eda8934..06f59d8 100644
--- a/server/hosts/cros_host.py
+++ b/server/hosts/cros_host.py
@@ -1603,12 +1603,8 @@
         self._start_powerd_if_needed()
 
 
-    def cleanup(self, reboot_cmd=None):
-        """Cleanup state on device.
-
-        @param  reboot_cmd: command to use to reboot device
-        @return nothing
-        """
+    def cleanup(self):
+        """Cleanup state on device."""
         self.run('rm -f %s' % client_constants.CLEANUP_LOGS_PAUSED_FILE)
         try:
             self.cleanup_services()
@@ -1617,12 +1613,13 @@
             logging.warning('Unable to restart ui.')
 
         # cleanup routines, i.e. reboot the machine.
-        super(CrosHost, self).cleanup(reboot_cmd=reboot_cmd)
+        super(CrosHost, self).cleanup()
 
         # Check if the rpm outlet was manipulated.
         if self.has_power():
             self._cleanup_poweron()
 
+
     def reboot(self, **dargs):
         """
         This function reboots the site host. The more generic
@@ -1631,7 +1628,7 @@
         sync should be finished in a short time during the reboot
         command.
         """
-        if dargs.get('reboot_cmd') is None:
+        if 'reboot_cmd' not in dargs:
             reboot_timeout = dargs.get('reboot_timeout', 10)
             dargs['reboot_cmd'] = ('sleep 1; '
                                    'reboot & sleep %d; '
@@ -1654,7 +1651,6 @@
 
         t0 = time.time()
         try:
-            logging.info("reboot cmd: %s", dargs.get('reboot_cmd'))
             super(CrosHost, self).reboot(**dargs)
         except Exception as e:
             metric_fields['success'] = False
diff --git a/server/hosts/remote.py b/server/hosts/remote.py
index dcb32c6..5f720a0 100644
--- a/server/hosts/remote.py
+++ b/server/hosts/remote.py
@@ -249,10 +249,10 @@
         self.log_op(self.OP_REBOOT, op_func)
 
 
-    def cleanup(self, reboot_cmd=None):
+    def cleanup(self):
         # pylint: disable=missing-docstring
         super(RemoteHost, self).cleanup()
-        self.reboot(reboot_cmd=reboot_cmd)
+        self.reboot()
 
 
     def get_tmp_dir(self, parent='/tmp'):