freezer: don't freeze WPRI-bound apps

If an app is bound with WPRI, it's expected to be responsive
to communication from other apps even though it could be in
the cached state. In this case, freezing an app that is bound via
a WPRI binding will cause some other app to hang because it will
not receive a message from those apps. As a result, don't freeze
these apps.

Test: webview-using apps work reliably when freezer is enabled
Bug: 150114383

Change-Id: I72f71bbe3dc54ed0c274d518250ac9d00310c2d5