Move random test util code from setup_common to random

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

src/test/validation_chainstate_tests.cpp

@@ -8,6 +8,7 @@
 #include <rpc/blockchain.h>
 #include <sync.h>
 #include <test/util/chainstate.h>
+#include <test/util/random.h>
 #include <test/util/setup_common.h>
 #include <uint256.h>
 #include <validation.h>