Merge bitcoin/bitcoin#33511: init: Fix Ctrl-C shutdown hangs during wait calls

c25a5e670b init: Signal m_tip_block_cv on Ctrl-C (Ryan Ofsky)
6a29f79006 test: Test SIGTERM handling during waitforblockheight call (Ryan Ofsky)

Pull request description:

  Signal `m_tip_block_cv` when Ctrl-C is pressed or `SIGTERM` is received, the same way it is currently signaled when the `stop` RPC is called. This lets RPC calls like `waitforblockheight` and IPC calls like `waitTipChanged` be interrupted, instead of waiting for their original timeouts and delaying shutdown.

  This issue was reported by plebhash in #33463. These hangs have been present since #30409. A similar bug was also fixed previously in Qt in #18452 and this PR simplifies that fix.

ACKs for top commit:
  Sjors:
    tACK c25a5e670b
  TheCharlatan:
    ACK c25a5e670b
  enirox001:
    Concept ACK c25a5e6

Tree-SHA512: 320aaa74fd308e826521c48c9a8aca4bd5f5530064cda2303d251d8e93e50c474bcd0db760ce04921928e73abefe4847aff797ac9ca7c89e74e5051bbed061cd

src/node/interfaces.cpp

@@ -132,7 +132,6 @@ public:
     }
     void appShutdown() override
     {
-        Interrupt(*m_context);
         Shutdown(*m_context);
     }
     void startShutdown() override
@@ -141,12 +140,7 @@ public:
         if (!(Assert(ctx.shutdown_request))()) {
             LogError("Failed to send shutdown signal\n");
         }
-
-        // Stop RPC for clean shutdown if any of waitfor* commands is executed.
-        if (args().GetBoolArg("-server", false)) {
-            InterruptRPC();
-            StopRPC();
-        }
+        Interrupt(*m_context);
     }
     bool shutdownRequested() override { return ShutdownRequested(*Assert(m_context)); };
     bool isSettingIgnored(const std::string& name) override