test: fix 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

PR-URL: #18382
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: Trott

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

@@ -306,7 +306,7 @@ function runTest(port, testIndex) {
     } else {
       server.close();
       successfulTests++;
-      runTest(port, nextTest++);
+      runTest(0, nextTest++);
     }
   }
 
@@ -325,7 +325,7 @@ function runTest(port, testIndex) {
             if (clientsCompleted === tcase.clients.length) {
               server.close();
               successfulTests++;
-              runTest(port, nextTest++);
+              runTest(0, nextTest++);
             }
           });
         }
@@ -337,7 +337,6 @@ function runTest(port, testIndex) {
 
 let nextTest = 0;
 runTest(0, nextTest++);
-runTest(0, nextTest++);
 
 
 process.on('exit', function() {