autotest: Increase sleep time in servohost reboot cmd to 5 seconds

We have been occasionally see labstation repair task fails in
reboot process due to get_boot_id call don't get execute within
1 second after send out reboot cmd. In most above cases, it took
1~2 seconds, so increase the sleep in reboot cmd to 5 second.

BUG=None
TEST=None

Change-Id: I35a2a95dda53bf8c0cab262f485529588d1c8651
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2019423
Tested-by: Garry Wang <xianuowang@chromium.org>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
Commit-Queue: Garry Wang <xianuowang@chromium.org>
diff --git a/server/hosts/base_servohost.py b/server/hosts/base_servohost.py
index 8f006a4..7c26826 100644
--- a/server/hosts/base_servohost.py
+++ b/server/hosts/base_servohost.py
@@ -37,7 +37,7 @@
     """Base host class for a host that manage servo(s).
      E.g. beaglebone, labstation.
     """
-    REBOOT_CMD = 'sleep 1; reboot & sleep 10; reboot -f'
+    REBOOT_CMD = 'sleep 5; reboot & sleep 10; reboot -f'
 
     TEMP_FILE_DIR = '/var/lib/servod/'