fix: move from plaintext to plain sasl mechanism

Author: wtrocki

source/rhoas/src/main/java/com/openshift/cloud/controllers/ManagedKafkaConnectionController.java

@@ -53,7 +53,7 @@ public UpdateControl<ManagedKafkaConnection> createOrUpdateResource(
       status.setUpdated(Instant.now().toString());
       status.setBootstrapServerHost(bootStrapHost);
       status.setServiceAccountSecretName(serviceAccountSecretName);
-      status.setSaslMechanism("PLAINTEXT");
+      status.setSaslMechanism("PLAIN");
       status.setSecurityProtocol("SASL_SSL");
 
       ConditionUtil.setAllConditionsTrue(resource.getStatus().getConditions());