Revert "Enable test CertificateManagerModelTest.ListsCertsFromPlatform"

This reverts commit 2e8d15a1.

Reason for revert: It's flaky on linux-trusty-rel
https://ci.chromium.org/p/chromium/builders/ci/linux-trusty-rel/4905

Original change's description:
> Enable test CertificateManagerModelTest.ListsCertsFromPlatform
> 
> The test was marked as flaky more then a year ago. The bug from the
> TODO is fixed and closed. And I was not able to reproduce the problem
> localy and via several runs on test servers.
> 
> Bug: 877416, 787602
> Change-Id: Iae0d816c94dedbfb0db779a7b492e7619eba1939
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1926480
> Reviewed-by: Matt Mueller <mattm@chromium.org>
> Commit-Queue: Michael Ershov <miersh@google.com>
> Cr-Commit-Position: refs/heads/master@{#718568}

TBR=mattm@chromium.org,miersh@google.com

Change-Id: I63c0b241b99b483b8c048f56074cb4cdd9a32467
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 877416, 787602, 1028183
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1933951Reviewed-by: Owen Min <zmin@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718669}

chrome/browser/certificate_manager_model_unittest.cc

@@ -113,7 +113,9 @@ class CertificateManagerModelTest : public testing::Test {
 
 // CertificateManagerModel correctly lists CA certificates from the platform NSS
 // Database.
-TEST_F(CertificateManagerModelTest, ListsCertsFromPlatform) {
+// TODO(https://crbug.com/787602): Re-enable this test when it is identified why
+// it was flaky.
+TEST_F(CertificateManagerModelTest, DISABLED_ListsCertsFromPlatform) {
   net::ScopedCERTCertificateList certs = CreateCERTCertificateListFromFile(
       net::GetTestCertsDirectory(), "websocket_cacert.pem",
       net::X509Certificate::FORMAT_AUTO);