Merge bitcoin/bitcoin#29367: wallet: Set descriptors flag after migrating blank wallets

3904123 tests: Test that descriptors flag is set for migrated blank wallets (Ava Chow)
072d506 wallet: Make sure that the descriptors flag is set for blank wallets (Ava Chow)

Pull request description:

  While rebasing #28710 after #28976 was merged, I realized that although blank wallets were being moved to sqlite, `WALLET_FLAG_DESCRIPTORS` was not being set so those blank wallets would still continue to be treated as legacy wallets.

  To fix that, just set the descriptor flags for blank wallets. Also added a test to catch this.

ACKs for top commit:
  epiccurious:
    Tested ACK 3904123.
  delta1:
    tested ACK 3904123
  ryanofsky:
    Code review ACK 3904123
  murchandamus:
    code review ACK 3904123

Tree-SHA512: 9f6fe9c1899ca387ab909b1bb6956cd6bc5acbf941686ddc6c061f9b1ceec2cc9d009ff472486fc86e963f6068f0e2f1ae96282e7c630193797a9734c4f424ab

Author: ryanofsky

src/wallet/wallet.cpp

@@ -4257,6 +4257,9 @@ util::Result<MigrationResult> MigrateLegacyToDescriptor(const std::string& walle
         success = local_wallet->IsWalletFlagSet(WALLET_FLAG_BLANK_WALLET);
         if (!success) {
             success = DoMigration(*local_wallet, context, error, res);
+        } else {
+            // Make sure that descriptors flag is actually set
+            local_wallet->SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
         }
     }
 

test/functional/wallet_migration.py

@@ -881,7 +881,7 @@ def test_blank(self):
         assert_equal(wallet.getwalletinfo()["blank"], True)
         wallet.migratewallet()
         assert_equal(wallet.getwalletinfo()["blank"], True)
-
+        assert_equal(wallet.getwalletinfo()["descriptors"], True)
 
     def test_avoidreuse(self):
         self.log.info("Test that avoidreuse persists after migration")