test: remove unused var in test-tls-server-verify

`connections` is assigned but never used. Remove it.

(This was missed by the linter in previous versions of ESLint but is
flagged by the current version. Updating the linter is contingent on
this change or some similar remedy landing.)

PR-URL: #7595
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: Trott

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

@@ -256,8 +256,6 @@ function runTest(port, testIndex) {
     rejectUnauthorized: tcase.rejectUnauthorized
   };
 
-  var connections = 0;
-
   /*
    * If renegotiating - session might be resumed and openssl won't request
    * client's certificate (probably because of bug in the openssl)
@@ -292,7 +290,6 @@ function runTest(port, testIndex) {
       return;
     }
 
-    connections++;
     if (c.authorized) {
       console.error(prefix + '- authed connection: ' +
                     c.getPeerCertificate().subject.CN);