Batch commands appear to not honor settingsfile-defined AuthenticationType

[jormdav]

We're testing a managed identity implementation, and have verified that ManagedIdentity is set as the AuthenticationType in our settingsfile, along with the expected values in the IdentityArgs section.

When the nodes attempt to run the batch command though, we see this in the Errors.log:

The --username and --password arguments are required when authentication type is set to Password or AzurePassword.;Returning error code: 1

Upon reviewing the command line on the batch job task, no --authtype arg is present, so it appears to presume SqlAuthentication, and we've purposefully neither of those values in our key vault.

We worked around in our test branch by shoehorning in the following into BatchManager.CompileCommanLines():

                if (cmdLine.AuthenticationArgs.AuthenticationType == AuthenticationType.ManagedIdentity)
                {
                    sb.Append(" --authtype ManagedIdentity ");
                }