[autotests] Don't check whether there is a /dev/dri/card0
Summary:
With EGL_MESA_platform_surfaceless we don't need a dri device anymore.
So we don't need to skip the tests if the device is missing. Instead the
tests verify that OpenGL compositing is used if requested.
Test Plan: ctest passes
Reviewers: KWin
Subscribers: kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D18014