summarize_loadtest: use argparse

This CLI parser isn't using any of the features of chromite's
commandline, so switch it to standard argparse to avoid the dep.

BUG=chromium:1049711
TEST=CQ passes

Change-Id: I6f40c0c4704ea1f8eea8e2ca21d26c8072f84d0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2044535
Reviewed-by: David Riley <davidriley@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/utils/summarize_loadtest.py b/utils/summarize_loadtest.py
index 65bd327..d85e428 100755
--- a/utils/summarize_loadtest.py
+++ b/utils/summarize_loadtest.py
@@ -13,7 +13,6 @@
 import sys
 
 import common
-from chromite.lib import commandline
 
 
 # Default keys to skip displaying.
@@ -38,7 +37,7 @@
 
 def get_parser():
     """Creates the argparse parser."""
-    parser = commandline.ArgumentParser(description=__doc__)
+    parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('infile', nargs='*', type=argparse.FileType('r'),
                         help='Path to JSON file to read.',
                         default=[sys.stdin])