Support TLS without mTLS feature in special case

[adeptvin1]

Description:
In the doc https://etcd.io/docs/v3.5/op-guide/security/ we can see that when we use TLS without --client-cert-auth etcd should accept incomming connection with cacert for gRPC and just work for HTTPS (I checked it, it's working).
But in this case we can't to use --trusted-ca-file. When you turn off --trusted-ca-file this functionality is working.
I found that in client/pkg/transport/listener.go you have next block:

	if info.TrustedCAFile != "" || info.ClientCertAuth {
		cfg.ClientAuth = tls.RequireAndVerifyClientCert
	}

Question:

Can you change || to && ? In my mind it will help to support TLS without mTLS for clients with --trusted-ca-file or it is not bug and we should to use mTLS with --trusted-ca-file?

Thanks