Netty client spans don't capture any span attributes on connection failure

[trask]

Not sure if it's even possible, but would be nice if Netty instrumentation could capture the same span attributes on connection failure as other http client instrumentation.

Currently it captures a span named CONNECT with no attributes:

opentelemetry-java-instrumentation/instrumentation/netty/netty-4.1/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/netty/v4_1/ChannelFutureListenerInstrumentation.java

Lines 66 to 67 in 0a34b2b

	Context errorContext = tracer().startSpan("CONNECT", SpanKind.CLIENT);
	tracer().endExceptionally(errorContext, cause);

And the netty tests suppress the normal test verification of span attributes for these requests:

  @Override
  boolean hasClientSpanAttributes(URI uri) {
    switch (uri.toString()) {
      case "http://localhost:61/": // unopened port
      case "http://www.google.com:81/": // dropped request
      case "https://192.0.2.1/": // non routable address
        return false
      default:
        return true
    }
  }