tests: set a socket timeout on replicator tests (#14457)

These nightly tests sometimes hang and are killed by timeout, instead of
passing or failing. Upon inspection of one of the failures, the hung
thread is stuck in `SocketDispatcher.read0()` native code, presumably
waiting for bytes that will never appear.

Instead, set a socket timeout for these tests, so that infinite hangs
(of this sort) will no longer happen: they may become failures instead.
Failures are better than hangs for many reasons.

Relates: #14454

Author: rmuir

lucene/replicator/src/test/org/apache/lucene/replicator/nrt/Connection.java

@@ -41,6 +41,7 @@ class Connection implements Closeable {
   public Connection(int tcpPort) throws IOException {
     this.destTCPPort = tcpPort;
     this.s = new Socket(InetAddress.getLoopbackAddress(), tcpPort);
+    this.s.setSoTimeout(30000);
     this.sockIn = s.getInputStream();
     this.in = new InputStreamDataInput(sockIn);
     this.bos = new BufferedOutputStream(s.getOutputStream());