fix: Exception message includes unnecessary class args

Fix misusages of ArgumentTypeError which causes a tuple of
class instance and error message string to be printed rather than just the
error message string itsself.

Change-Id: I0e997f86bb6603930cc92e90efcb48155f62ffb5
Closes-bug: #1551426

Author: Jas

openstackclient/common/parseractions.py

@@ -89,7 +89,7 @@ def __call__(self, parser, namespace, values, metavar=None):
             else:
                 msg = ("Expected key=value pairs separated by comma, "
                        "but got: %s" % (str(kv)))
-                raise argparse.ArgumentTypeError(self, msg)
+                raise argparse.ArgumentTypeError(msg)
 
         # Check key validation
         valid_keys = self.required_keys | self.optional_keys
@@ -160,4 +160,4 @@ def __call__(self, parser, namespace, values, option_string=None):
             setattr(namespace, self.dest, values)
         except Exception:
             msg = "%s expected a non-negative integer" % (str(option_string))
-            raise argparse.ArgumentTypeError(self, msg)
+            raise argparse.ArgumentTypeError(msg)