test: fix test/parallel/test-tls-server-verify.js on Windows CI

The test runs two test cases at a time. This is not relevant to what the
test is actually testing. Not sure why doing it that way causes a
deadlock on some Windows servers, but running one at a time fixes it.

Fixes: #18269

test/parallel/test-tls-server-verify.js

@@ -327,7 +327,7 @@ function runTest(port, testIndex) {
     } else {
       server.close();
       successfulTests++;
-      runTest(port, nextTest++);
+      runTest(0, nextTest++);
     }
   }
 
@@ -345,7 +345,7 @@ function runTest(port, testIndex) {
           if (clientsCompleted === tcase.clients.length) {
             server.close();
             successfulTests++;
-            runTest(port, nextTest++);
+            runTest(0, nextTest++);
           }
         });
       }
@@ -356,7 +356,6 @@ function runTest(port, testIndex) {
 
 let nextTest = 0;
 runTest(0, nextTest++);
-runTest(0, nextTest++);
 
 
 process.on('exit', function() {