Merge bitcoin/bitcoin#31486: fuzz: Abort when using global PRNG without re-seed

fae63bf130 fuzz: Clarify that only SeedRandomStateForTest(SeedRand::ZEROS) is allowed (MarcoFalke)
fa18acb457 fuzz: Abort when using global PRNG without re-seed (MarcoFalke)
fa7809aeab fuzz: Add missing SeedRandomStateForTest(SeedRand::ZEROS) (MarcoFalke)

Pull request description:

  This is the first step toward improving fuzz stability and determinism (https://github.com/bitcoin/bitcoin/issues/29018).

  A fuzz target using the global test-only PRNG will now abort if the seed is re-used across fuzz inputs.

  Also, temporarily add `SeedRandomStateForTest(SeedRand::ZEROS)` to all affected fuzz targets. This may slow down the libfuzzer leak detector, but it will disable itself after some time, or it can be disabled explicitly with `-detect_leaks=0`.

  In a follow-up, each affected fuzz target can be stripped of the global random use and a local `RandomMixin` (or similar) can be added instead.

  (Can be tested by removing any one of the re-seed calls and observing a fuzz abort)

ACKs for top commit:
  hodlinator:
    ACK fae63bf130
  dergoegge:
    utACK fae63bf130
  marcofleon:
    Tested ACK fae63bf130

Tree-SHA512: 4a0db69af7f715408edf4f8b08b44f34ce12ee2c79d33b336ad19a6e6bd079c4ff7c971af0a3efa428213407c1171f4e2837ec6a2577086c2f94cd15618a0892

src/test/fuzz/process_message.cpp

@@ -52,6 +52,7 @@ void initialize_process_message()
 
 FUZZ_TARGET(process_message, .init = initialize_process_message)
 {
+    SeedRandomStateForTest(SeedRand::ZEROS);
     FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
 
     ConnmanTestMsg& connman = *static_cast<ConnmanTestMsg*>(g_setup->m_node.connman.get());