test: move remaining random test util code from setup_common to random

and drop the util/random dependency on util/setup_common.

This improves code separation and avoids creating a circular dependency if
setup_common needs to call the util/random functions.

src/test/miniscript_tests.cpp

@@ -6,6 +6,7 @@
 #include <string>
 #include <vector>
 
+#include <test/util/random.h>
 #include <test/util/setup_common.h>
 #include <boost/test/unit_test.hpp>