Disable QuickCheck and unit tests.

The current QuickCheck state machine is as follows:

Wait -> QC --ok--> FetchDHCP --fail--> FetchDNS --fail--> Fail
         |             |                 |
         |             --------ok--------------ok-------> Verify
         |
         |--fail--> Fail

What this means is that if QuickCheck fails, we will never try a DHCP fetch for
the WPAD script, even though that could still succeed as QuickCheck only tests
for the presence of a DNS source.

In future, the state machine should look like this:

Wait -> FetchDHCP --fail--> QC --ok--> FetchDNS --fail--> Fail
        |                   |            |
        |                   |            |--ok--> Verify
        |                   |
        |                   |--fail--> Fail
        |
        |--ok--> Verify

BUG=318730
TEST=unit,trybot

Review URL: https://codereview.chromium.org/65313004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235187 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235187