NetworkService: Suppress two browsertests that are always failing

These tests almost never succeeded:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=network_service_browser_tests&tests=SSLUITestCommittedInterstitials.ErrorPageType%2CSafeBrowsingTriggeredInterceptingBrowserTest.AbusiveMetadata

SSLUITestCommittedInterstitials.ErrorPageType
SafeBrowsingTriggeredInterceptingBrowserTest.AbusiveMetadata

TBR=jam@chromium.org
NOTRY=true

Bug: 729848
Change-Id: Icc2f009f2825f72e49c9fcbc87eb5843258d0b6a
Reviewed-on: https://chromium-review.googlesource.com/746624Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512789}

testing/buildbot/filters/mojo.fyi.network_browser_tests.filter

@@ -116,6 +116,7 @@
 -ResourcePrefetchPredictorPrefetchingBrowserTest.Simple
 -SSLUIWorkerFetchTest.TestUnsafeContentsInWorkerWithUserException/2
 -SSLUIWorkerFetchTest.TestUnsafeContentsInWorkerWithUserException/3
+-SSLUITestCommittedInterstitials.ErrorPageType
 -SafeBrowsingBlockingPageBrowserTestWithThreatTypeAndIsolationSetting/SafeBrowsingBlockingPageBrowserTest.SecurityStateGoBackOnSubresourceInterstitial/0
 -SafeBrowsingBlockingPageBrowserTestWithThreatTypeAndIsolationSetting/SafeBrowsingBlockingPageBrowserTest.SecurityStateGoBackOnSubresourceInterstitial/1
 -SafeBrowsingBlockingPageBrowserTestWithThreatTypeAndIsolationSetting/SafeBrowsingBlockingPageBrowserTest.SecurityStateGoBackOnSubresourceInterstitial/2
@@ -128,6 +129,7 @@
 -SafeBrowsingTriggeredPopupBlockerBrowserTest.MultipleNavigations
 -SafeBrowsingTriggeredPopupBlockerBrowserTest.WarningAllowCreatingNewWindows_LogsToConsole
 -SafeBrowsingTriggeredPopupBlockerBrowserTest.WarningDoNotBlockCreatingNewWindows_LogsToConsole
+-SafeBrowsingTriggeredInterceptingBrowserTest.AbusiveMetadata
 -SavePageBrowserTest.SaveUnauthorizedResource
 -ServiceWorkerPaymentAppFactoryBrowserTest.AllOringsSupported
 -ServiceWorkerPaymentAppFactoryBrowserTest.SupportedOrigin