Disable WebViewCaptureTest.Shim_ScreenshotCapture to make try/CQ work

Possibly be a bot issue, but it's piling up tons of jobs in CQ,
so let me tentatively disable this to make things saner.

(Feel free to revert this change if this should just succeed)

BUG=330146
TBR=sadrul

Review URL: https://codereview.chromium.org/110633006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242056 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242056