[autotest] Do not keep the ownership of files rsync to DUT

Add option --no-o --no-g to rsync option.

BUG=chromium:333114
TEST=test_that 172.22.14.6 dummy_Pass --board lumpy
verify owner and group of files in /usr/local/autotest/ are both root.

Change-Id: I45391b910b7968556ca45b48f94af2a5a5636280
Reviewed-on: https://chromium-review.googlesource.com/186152
Tested-by: Dan Shi <[email protected]>
Reviewed-by: Alex Miller <[email protected]>
Reviewed-by: Jorge Lucangeli Obes <[email protected]>
Commit-Queue: Dan Shi <[email protected]>
diff --git a/server/hosts/abstract_ssh.py b/server/hosts/abstract_ssh.py
index 7af5a2e..b731b21 100644
--- a/server/hosts/abstract_ssh.py
+++ b/server/hosts/abstract_ssh.py
@@ -104,7 +104,8 @@
             symlink_flag = ""
         else:
             symlink_flag = "-L"
-        command = "rsync %s %s --timeout=1800 --rsh='%s' -az %s %s"
+        command = ("rsync %s %s --timeout=1800 --rsh='%s' -az --no-o --no-g "
+                   "%s %s")
         return command % (symlink_flag, delete_flag, ssh_cmd,
                           " ".join(sources), dest)