scripted-diff: Replace MilliSleep with UninterruptibleSleep

This is safe because MilliSleep is never executed in a boost::thread,
the only type of thread that is interruptible.

* The RPC server uses std::thread
* The wallet is either executed in an RPC thread or the main thread
* bitcoin-cli, benchmarks and tests are only one thread (the main thread)

-BEGIN VERIFY SCRIPT-
sed -i --regexp-extended -e 's/MilliSleep\((\S+)\);/UninterruptibleSleep(std::chrono::milliseconds{\1});/g' $(git grep -l MilliSleep)
-END VERIFY SCRIPT-

src/rpc/server.cpp

@@ -169,7 +169,7 @@ UniValue stop(const JSONRPCRequest& jsonRequest)
     // this reply will get back to the client.
     StartShutdown();
     if (jsonRequest.params[0].isNum()) {
-        MilliSleep(jsonRequest.params[0].get_int());
+        UninterruptibleSleep(std::chrono::milliseconds{jsonRequest.params[0].get_int()});
     }
     return PACKAGE_NAME " stopping";
 }