redfish: extended: dump: fix "Verify Download BMC Dump" test failed

Symptom:
"Verify Download BMC Dump" test item in test_bmc_dump.robot got failed.

Root cause:
From test report that error message is
JSONDecodeError: Expecting value: line 1 column 1 (char 0).
Due to this test item using REST method "Create User Initiated Dump"
to create bmc dump and got failed. Thus, "Get The Dump Id" return unexpected value.

Solution:
Using Redfish method to create BMC Dump according current bmcweb design.

Tested:
Run robot "Verify Download BMC Dump" of test_bmc_dump.robot

Signed-off-by: Tim Lee <timlee660101@gmail.com>
Change-Id: I14b25408277809d5de6148fed91a36b85ede479e
diff --git a/redfish/extended/test_websocket.robot b/redfish/extended/test_websocket.robot
index 6ab49f2..afb86e6 100755
--- a/redfish/extended/test_websocket.robot
+++ b/redfish/extended/test_websocket.robot
@@ -78,7 +78,7 @@
 
     Redfish Delete All BMC Dumps
     Start Websocket Monitor  dump
-    ${dump_id}=  Create User Initiated BMC Dump Using Redfish
+    ${dump_id}=  Create User Initiated BMC Dump Via Redfish
     Check Existence Of BMC Dump File  ${dump_id}
 
     # Check that the monitor received notification of the dump.