CI: Do not run build and test on nightly builds. Except test while building docker image

Asi muzeme usetrit trochu vykonu zbytecnou dvoji kompilaci.

extra/docker/Dockerfile.master

@@ -30,7 +30,7 @@ RUN	cmake \
 		-DCMAKE_INSTALL_PREFIX=$BASEDIR/install \
 		.. && \
 	make -j $(grep -c processor /proc/cpuinfo) && \
-	make test && \
+	make test ARGS="-j $(grep -c processor /proc/cpuinfo)" && \
 	make install