Disable PaymentAppBrowserTests under the network service.

Two more of these were recently, both of which are failing, and all the
old tests using the fixture are failing, too, so simplest just to
disable them all.

TBR=yzshen@chromium.org
NOTRY=true

Bug: None
Change-Id: I7e4751021dce0d2383e46a63ab7305b5e6e58676
Reviewed-on: https://chromium-review.googlesource.com/598111
Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491373}

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

@@ -86,9 +86,7 @@
 -NavigationHandleImplBrowserTest.ErrorCodeOnRedirect
 -NavigationHandleImplBrowserTest.RedirectToRendererDebugUrl
 -ParallelDownloadTest.ParallelDownloadComplete
--PaymentAppBrowserTest.PaymentAppInvocation
--PaymentAppBrowserTest.PaymentAppInvocationAndFailed
--PaymentAppBrowserTest.PaymentAppOpenWindowFailed
+-PaymentAppBrowserTest.*
 -PlzNavigateNavigationHandleImplBrowserTest.ErrorPageNetworkError
 -PowerMonitorTest.TestGpuProcess
 -PowerMonitorTest.TestRendererProcess