Automation fix for Network sub menu

Changes:
    - Modified "Delete DNS Servers And Verify" keyword
    - Modified "Add DNS Servers And Verify"
    - Removed "DNS Test Setup Execution" keyword from
      redfish/managers/test_bmc_network_conf.robot
      and added in lib/bmc_network_utils.robot

Tested:
    - Ran successfully
      gui/gui_test/settings_menu
      /test_network_sub_menu.robot
      gui/lib/gui_resource.robot
      lib/bmc_network_utils.robot
      redfish/managers/test_bmc_network_conf.robot

Change-Id: I6ffcb7aba29312fa1e4cc843453bca49cd44d0f1
Signed-off-by: Megha G N <Megha.G.N@ibm.com>
diff --git a/gui/lib/gui_resource.robot b/gui/lib/gui_resource.robot
index 4a22f34..d53091d 100644
--- a/gui/lib/gui_resource.robot
+++ b/gui/lib/gui_resource.robot
@@ -194,6 +194,9 @@
     ${cli_name_servers}=  CLI Get Nameservers
     ${cmd_status}=  Run Keyword And Return Status
     ...  List Should Contain Sub List  ${cli_name_servers}  ${dns_server}
+    Run Keyword If  '${expected_status}' == '${HTTP_OK}'
+    ...  Should Be True  ${cmd_status} == ${True}
+    ...  ELSE  Should Not Be True  ${cmd_status}
 
 
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