KAFKA-19017: Changed consumer.config to command-config in verifiable_share_consumer.py (#19254)

In an earlier PR, the flag --consumer.config in
VerifiableShareConsumer.java was changed to --command-config. This PR
makes the same change when VerifiableShareConsumer is used in
verifiable_share_consumer.py.

Reviewers: Andrew Schofield <aschofield@confluent.io>

Author: chirag-wadhwa5

tests/kafkatest/services/verifiable_share_consumer.py

@@ -236,7 +236,7 @@ def start_cmd(self, node):
         if self.max_messages > 0:
             cmd += " --max-messages %s" % str(self.max_messages)
 
-        cmd += " --consumer.config %s" % VerifiableShareConsumer.CONFIG_FILE
+        cmd += " --command-config %s" % VerifiableShareConsumer.CONFIG_FILE
         cmd += " 2>> %s | tee -a %s &" % (VerifiableShareConsumer.STDOUT_CAPTURE, VerifiableShareConsumer.STDOUT_CAPTURE)
         return cmd