Removed unused PING_IPV4_COMMAND etc

PING_IPV4_COMMAND, PING_IPV6_COMMAND and PING_PACKET_LOSS_REGEX had
been added since Ia34d7c75ad05f7658d1abb7bebeb1bbd271fd089 (2012),
but they were never used at all.
This patch removes them for the cleanup.

Change-Id: Ide56a0eaa6727d41fb35fb287dcf919828db05e5
diff --git a/tempest/common/utils/__init__.py b/tempest/common/utils/__init__.py
index b6565d1..84e31d0 100644
--- a/tempest/common/utils/__init__.py
+++ b/tempest/common/utils/__init__.py
@@ -19,10 +19,6 @@
 
 CONF = config.CONF
 
-PING_IPV4_COMMAND = 'ping -c 3 '
-PING_IPV6_COMMAND = 'ping6 -c 3 '
-PING_PACKET_LOSS_REGEX = '(\d{1,3})\.?\d*\% packet loss'
-
 
 class DataUtils(object):
     def __getattr__(self, attr):