Unset all env variables related to KDE session in integration tests

Summary:
When running ctest in my session a few OpenGL/waylandonly tests crashed
on tear down. This does neither happen on build.kde.org nor when running
ctest in a tty. Comparing the env variables of tty and session pointed
to the session variables. Unsetting those makes the test not crash. This
makes sense as e.g. plasma-integration no longer gets loaded.

As our test suite is intended to test KWin and not plasma-integration or
gnome integration we should have a clean and reproducable environment,
so the variables are unset.

Test Plan: 100% tests passed, 0 tests failed out of 130

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D16939

autotests/integration/kwin_wayland_test.h

@@ -193,6 +193,10 @@ int main(int argc, char *argv[]) \
     setenv("QT_QPA_PLATFORM", "wayland-org.kde.kwin.qpa", true); \
     setenv("QT_QPA_PLATFORM_PLUGIN_PATH", QFileInfo(QString::fromLocal8Bit(argv[0])).absolutePath().toLocal8Bit().constData(), true); \
     setenv("KWIN_FORCE_OWN_QPA", "1", true); \
+    qunsetenv("KDE_FULL_SESSION"); \
+    qunsetenv("KDE_SESSION_VERSION"); \
+    qunsetenv("XDG_SESSION_DESKTOP"); \
+    qunsetenv("XDG_CURRENT_DESKTOP"); \
     DPI; \
     KWin::WaylandTestApplication app(OperationMode, argc, argv); \
     app.setAttribute(Qt::AA_Use96Dpi, true); \