test: Fix clang-tidy issues in new Vault+AMM tests

- AMM_test: directly include <xrpl/protocol/MPTIssue.h>
  (misc-include-cleaner).
- Vault_test::testMutateCanTransferAfterDeposit: declare local Vault
  const (misc-const-correctness).

src/test/app/AMM_test.cpp

@@ -37,6 +37,7 @@
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/MPTIssue.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/Quality.h>
 #include <xrpl/protocol/Rules.h>

src/test/app/Vault_test.cpp

@@ -6183,7 +6183,7 @@ class Vault_test : public beast::unit_test::suite
         env(pay(issuer, bob, asset(100'000)));
         env.close();
 
-        Vault vault{env};
+        Vault const vault{env};
         auto [createTx, vaultKeylet] = vault.create({.owner = alice, .asset = asset});
         env(createTx);
         env.close();