test: common: Fix MassiveParallelTest to not fail under slow emulation

Thisi test occassionally failed on qemu emulating Alpine Linux
loongarch64.

Reduce the number of connect calls, and stop the server after shutting
down the threads repsonsible for accumulating requests.

junixsocket-common/src/test/java/org/newsclub/net/unix/domain/MassiveParallelTest.java

@@ -51,6 +51,7 @@
 
 import com.kohlschutter.annotations.compiletime.SuppressFBWarnings;
 import com.kohlschutter.testutil.TestAbortedNotAnIssueException;
+import com.kohlschutter.util.SystemPropertyUtil;
 
 @AFSocketCapabilityRequirement(AFSocketCapability.CAPABILITY_UNIX_DOMAIN)
 @SuppressWarnings({
@@ -72,9 +73,15 @@ public void testAcceptConnect() throws Exception {
     }
     // number of connections to perform
     // final int numConnections = 1_000;
-    final int numConnections = 10_000;
+    // final int numConnections = 10_000;
     // final int numConnections = 100_000;
     // final int numConnections = 1_000_000;
+    final int numConnections = SystemPropertyUtil.getIntSystemProperty(
+        "selftest.MassiveParallelTest.numConnections", 1000);
+    if (numConnections <= 0) {
+      throw new TestAbortedNotAnIssueException("Skipping test due to numConnections="
+          + numConnections);
+    }
 
     // limit the number of concurrently active servers/clients
     // so we don't run out of file descriptors (the limit could be as low as 256)
@@ -164,7 +171,6 @@ public void run() {
       }
 
       boolean stopped = server.cl.await(10, TimeUnit.SECONDS);
-      server.stop();
       if (!stopped) {
         List<Runnable> remainingClients = esClients.shutdownNow();
         List<Runnable> remainingServers = server.esServers.shutdownNow();
@@ -174,6 +180,7 @@ public void run() {
               + remainingClients.size());
         }
       }
+      server.stop();
 
       long elapsed = (System.currentTimeMillis() - startTime);
       int completed = server.completed.intValue();