Merge bitcoin/bitcoin#28224: shutdown: Destroy kernel last, make test shutdown order consistent

c1144f0076 tests: Reset node context members on ~BasicTestingSetup (TheCharlatan)
9759af17ff shutdown: Destroy kernel last (TheCharlatan)

Pull request description:

  The destruction/resetting of node context members in the tests should roughly follow the behavior of the `Shutdown` function in `init.cpp`.

  This was originally requested by MarcoFalke in this [comment](https://github.com/bitcoin/bitcoin/pull/25065#discussion_r890161249) in response to the [original pull request](https://github.com/bitcoin/bitcoin/pull/25065) introducing the `kernel::Context`.

ACKs for top commit:
  maflcko:
    ACK c1144f0076 🗣
  achow101:
    ACK c1144f0076
  ryanofsky:
    Code review ACK c1144f0076. No code changes since last review, just updated commits and descriptions

Tree-SHA512: 819bb85ff82a5c6c60e429674d5684f3692fe9062500d00a87b361cc59e6bda145be21b5a4466dee6791faed910cbde4d26baab325bf6daa1813af13a63588ff

src/init.cpp

@@ -343,11 +343,11 @@ void Shutdown(NodeContext& node)
     node.chain_clients.clear();
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
-    node.kernel.reset();
     node.mempool.reset();
     node.fee_estimator.reset();
     node.chainman.reset();
     node.scheduler.reset();
+    node.kernel.reset();
 
     try {
         if (!fs::remove(GetPidFile(*node.args))) {