Merge bitcoin/bitcoin#32023: wallet: removed duplicate call to GetDescriptorScriptPubKeyMan

55b931934a removed duplicate calling of GetDescriptorScriptPubKeyMan (Saikiran)

Pull request description:

  Removed duplicate call to GetDescriptorScriptPubKeyMan and
  Instead of checking linearly I have used find method so time complexity reduced significantly for GetDescriptorScriptPubKeyMan
  after this fix improved performance of importdescriptor part refs https://github.com/bitcoin/bitcoin/issues/32013.

  **Steps to reproduce in testnet environment**

  **Input size:** 2 million address in the wallet

  **Step1:** call importaddresdescriptor rpc method
  observe the time it has taken.

  **With the provided fix:**
  Do the same steps again
  observe the time it has taken.

  There is a huge improvement in the performance. (previously it may take 5 to 6 seconds now it will take 1 seconds or less)

  main changes i've made during this pr:

  1. remove duplicate call to GetDescriptorScriptPubKeyMan method
  2. And inside GetDescriptorScriptPubKeyMan method previously we checking **each address linearly** so each time it is calling HasWallet method which has aquired lock.
  3. Now i've modified this logic call **find method on the map (O(logn)**) time it is taking, so only once we calling HasWallet method.

  **Note:** Smaller inputs in the wallet you may not see the issue but huge wallet size it will definitely impact the performance.

ACKs for top commit:
  achow101:
    ACK 55b931934a
  w0xlt:
    ACK https://github.com/bitcoin/bitcoin/pull/32023/commits/55b931934a34bab11446e8eed7bdaef92bb056de

Tree-SHA512: 4a7fdbcbb4e55bd034e9cf28ab4e7ee3fb1745fc8847adb388c98a19c952a1fb66d7b54f0f28b4c2a75a42473923742b4a99fb26771577183a98e0bcbf87a8ca

src/qt/test/wallettests.cpp

@@ -223,7 +223,8 @@ std::shared_ptr<CWallet> SetupDescriptorsWallet(interfaces::Node& node, TestChai
     assert(descs.size() == 1);
     auto& desc = descs.at(0);
     WalletDescriptor w_desc(std::move(desc), 0, 0, 1, 1);
-    if (!wallet->AddWalletDescriptor(w_desc, provider, "", false)) assert(false);
+    auto spk_manager = *Assert(wallet->AddWalletDescriptor(w_desc, provider, "", false));
+    assert(spk_manager);
     CTxDestination dest = GetDestinationForKey(test.coinbaseKey.GetPubKey(), wallet->m_default_address_type);
     wallet->SetAddressBook(dest, "", wallet::AddressPurpose::RECEIVE);
     wallet->SetLastBlockProcessed(105, WITH_LOCK(node.context()->chainman->GetMutex(), return node.context()->chainman->ActiveChain().Tip()->GetBlockHash()));