random: drop ad-hoc Shuffle in favor of std::shuffle

Benchmarks show it is no longer faster with modern standard C++ libraries,
and the debug-mode failure due to self-move has been fixed as well.

src/test/fuzz/random.cpp

@@ -26,6 +26,5 @@ FUZZ_TARGET(random)
     (void)fast_random_context();
 
     std::vector<int64_t> integrals = ConsumeRandomLengthIntegralVector<int64_t>(fuzzed_data_provider);
-    Shuffle(integrals.begin(), integrals.end(), fast_random_context);
     std::shuffle(integrals.begin(), integrals.end(), fast_random_context);
 }