Lower message severity of self test log messages

It is reported that the self test produces false positives with some
drivers. At quick glance, there is nothing in particular extremely wrong
with the test. Since not a lot can be done about the test except making
changes in drivers, the severity of the log messages should be lowered
to avoid polluting logs.

libkwineffects/kwinglutils.cpp

@@ -597,11 +597,11 @@ bool ShaderManager::selfTest()
         return true;
     }
     if (GLPlatform::instance()->isNvidia() && GLPlatform::instance()->glRendererString().contains("Quadro")) {
-        qCWarning(LIBKWINGLUTILS) << "Skipping self test as it is reported to return false positive results on Quadro hardware";
+        qCDebug(LIBKWINGLUTILS) << "Skipping self test as it is reported to return false positive results on Quadro hardware";
         return true;
     }
     if (GLPlatform::instance()->isMesaDriver() && GLPlatform::instance()->mesaVersion() >= kVersionNumber(17, 0)) {
-        qCWarning(LIBKWINGLUTILS) << "Skipping self test as it is reported to return false positive results on Mesa drivers";
+        qCDebug(LIBKWINGLUTILS) << "Skipping self test as it is reported to return false positive results on Mesa drivers";
         return true;
     }