Move random test util code from setup_common to random

as many of the unit tests don't use this code

src/test/transaction_tests.cpp

@@ -22,6 +22,7 @@
 #include <script/standard.h>
 #include <streams.h>
 #include <test/util/json.h>
+#include <test/util/random.h>
 #include <test/util/script.h>
 #include <test/util/transaction_utils.h>
 #include <util/strencodings.h>