Pass ca_certs to VNC tests

Related-Prod: PRODX-27390
Change-Id: I1b7e30764ec1fc801cbd3d8afd5a9e6cdc8f01ec
(cherry picked from commit 50af44e78ce0c3f5abeacd551a56645fc809b840)
diff --git a/tempest/api/compute/servers/test_novnc.py b/tempest/api/compute/servers/test_novnc.py
index 1308b19..c90aea8 100644
--- a/tempest/api/compute/servers/test_novnc.py
+++ b/tempest/api/compute/servers/test_novnc.py
@@ -64,7 +64,15 @@
 
     def _validate_novnc_html(self, vnc_url):
         """Verify we can connect to novnc and get back the javascript."""
-        resp = urllib3.PoolManager().request('GET', vnc_url)
+        cert_params = {}
+
+        if CONF.identity.disable_ssl_certificate_validation:
+            cert_params['cert_reqs'] = "CERT_NONE"
+        else:
+            cert_params["cert_reqs"] = "CERT_REQUIRED"
+            cert_params["ca_certs"] = CONF.identity.ca_certificates_file
+
+        resp = urllib3.PoolManager(**cert_params).request('GET', vnc_url)
         # Make sure that the GET request was accepted by the novncproxy
         self.assertEqual(resp.status, 200, 'Got a Bad HTTP Response on the '
                          'initial call: ' + str(resp.status))