enable SubresourceFilterBrowserTest.FailedProvisionalLoadInMainframe on network_browser_tests

The test depended on "host_resolver()->AddSimulatedFailure", which wasn't handled by the network service tests until https://chromium.googlesource.com/chromium/src/+/9690e08467150d094fd74f3db673c995cec2b78c

Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: Id64f0eed2933a89d093a8f2328a1868009a57998
Reviewed-on: https://chromium-review.googlesource.com/1180472Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584253}

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

@@ -8,7 +8,6 @@
 # Uncategorized timeouts or test failures.
 -ProxySettingsApiTest.ProxyEventsInvalidProxy
 -RegisterProtocolHandlerBrowserTest.CustomHandler
--SubresourceFilterBrowserTest.FailedProvisionalLoadInMainframe
 
 # Domain Reliability has yet to be hookup to the NetworkService.
 # https://crbug.com/853251