Disable flaky RestoreOnStartupPolicyTestInstance/RestoreOnStartupPolicyTest.RunTest

This was marked as flaky on Linux only but is also flaking on Mac and Windows:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=RestoreOnStartupPolicyTestInstance%2FRestoreOnStartupPolicyTest.RunTest%2F2

TBR=thomasanderson@chromium.org

Bug: 701023
Change-Id: I5018441e068aa3ea968290eace5537bf7361d6b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1816654Reviewed-by: Leonard Grey <lgrey@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698900}

chrome/browser/policy/policy_browsertest.cc

@@ -2982,13 +2982,8 @@ IN_PROC_BROWSER_TEST_P(RestoreOnStartupPolicyTest, PRE_RunTest) {
   }
 }
 
-// Flaky on Linux; see https://crbug.com/701023.
-#if defined(OS_LINUX)
-#define MAYBE_RunTest DISABLED_RunTest
-#else
-#define MAYBE_RunTest RunTest
-#endif
-IN_PROC_BROWSER_TEST_P(RestoreOnStartupPolicyTest, MAYBE_RunTest) {
+// Flaky; see https://crbug.com/701023.
+IN_PROC_BROWSER_TEST_P(RestoreOnStartupPolicyTest, DISABLED_RunTest) {
   TabStripModel* model = browser()->tab_strip_model();
   int size = static_cast<int>(expected_urls_.size());
   EXPECT_EQ(size, model->count());
@@ -3003,7 +2998,6 @@ IN_PROC_BROWSER_TEST_P(RestoreOnStartupPolicyTest, MAYBE_RunTest) {
       EXPECT_EQ(expected_urls_[i], web_contents->GetURL());
   }
 }
-#undef MAYBE_RunTest
 
 INSTANTIATE_TEST_SUITE_P(
     RestoreOnStartupPolicyTestInstance,