Merge #21415: refactor: remove Optional & nullopt

ebc4ab721b refactor: post Optional<> removal cleanups (fanquake)
57e980d13c scripted-diff: remove Optional & nullopt (fanquake)

Pull request description:

  Same rationale & motivation as #21404, which turned out to be quite low in the number of potential conflicts. Lets see what the bot has to say here.

ACKs for top commit:
  practicalswift:
    cr ACK ebc4ab721b: patch looks correct
  jnewbery:
    utACK ebc4ab721b
  laanwj:
    Code review ACK ebc4ab721b

Tree-SHA512: 550fbeef09b9d35ddefaa805d1755c18c8fd499c4b0f77ebfece8c20296a7abd1cf6c699e2261f92fe3552deeb7555ec2a2287ffe3ab9e98bb9f8612a4d43be3

src/qt/test/addressbooktests.cpp

@@ -112,7 +112,7 @@ void TestAddAddressesToSendBook(interfaces::Node& node)
     ClientModel clientModel(node, &optionsModel);
     AddWallet(wallet);
     WalletModel walletModel(interfaces::MakeWallet(wallet), clientModel, platformStyle.get());
-    RemoveWallet(wallet, nullopt);
+    RemoveWallet(wallet, std::nullopt);
     EditAddressDialog editAddressDialog(EditAddressDialog::NewSendingAddress);
     editAddressDialog.setModel(walletModel.getAddressTableModel());
 

src/qt/test/wallettests.cpp

@@ -167,7 +167,7 @@ void TestGUI(interfaces::Node& node)
     ClientModel clientModel(node, &optionsModel);
     AddWallet(wallet);
     WalletModel walletModel(interfaces::MakeWallet(wallet), clientModel, platformStyle.get());
-    RemoveWallet(wallet, nullopt);
+    RemoveWallet(wallet, std::nullopt);
     sendCoinsDialog.setModel(&walletModel);
     transactionView.setModel(&walletModel);