Exclude ProxyAuthOnUserBoardScreenTest.ProxyAuthDialogOnUserBoardScreen/1 under MSan

TBR=paulmeyer@chromium.org
BUG=481651
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_msan_rel_ng

Review URL: https://codereview.chromium.org/1102403003

Cr-Commit-Position: refs/heads/master@{#327194}

chrome/browser/chromeos/login/proxy_auth_dialog_browsertest.cc

@@ -128,6 +128,11 @@ IN_PROC_BROWSER_TEST_P(ProxyAuthOnUserBoardScreenTest,
 
 INSTANTIATE_TEST_CASE_P(ProxyAuthOnUserBoardScreenTestSuite,
                         ProxyAuthOnUserBoardScreenTest,
+// Times out under MSan: https://crbug.com/481651
+#if defined(MEMORY_SANITIZER)
+                        testing::Values(false));
+#else
                         testing::Bool());
+#endif
 
 }  // namespace chromeos