C*4 includes port in IP sent into Connection metric

[serban21]

Testing with latest C*4:

java.lang.IllegalArgumentException: '127.0.0.1_7000' is not an IP string literal.
	at com.google.common.net.InetAddresses.forString(InetAddresses.java:153)
	at com.zegelin.cassandra.exporter.MetadataFactory.endpointLabels(MetadataFactory.java:76)
	at com.zegelin.cassandra.exporter.FactoriesSupplier.lambda$connectionMetric$19(FactoriesSupplier.java:502)
	at com.zegelin.cassandra.exporter.FactoriesSupplier$FactoryBuilder.lambda$withLabelMaker$0(FactoriesSupplier.java:75)
	at com.zegelin.cassandra.exporter.FactoriesSupplier$FactoryBuilder.lambda$build$1(FactoriesSupplier.java:101)
	at com.zegelin.cassandra.exporter.Harvester.lambda$registerMBean$0(Harvester.java:177)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

The port is included due to CASSANDRA-7544 and apache/cassandra@59b5b6b. A possible solution might be to replace InetAddresses with HostAndPort