wallet: Clarify IsEquivalentTo is actually checking malleation

### src/wallet/transaction.cpp
@@ -11,7 +11,7 @@
 using interfaces::FoundBlock;
 
 namespace wallet {
-bool CWalletTx::IsEquivalentTo(const CWalletTx& _tx) const
+bool CWalletTx::IsMalleation(const CWalletTx& _tx) const
 {
     return GetTx()->Equals(*_tx.GetTx(), {.include_script_sig = false, .include_witness_data = false});
 }

### src/wallet/transaction.h
@@ -366,8 +366,9 @@ class CWalletTx
         m_cached_from_me = std::nullopt;
     }
 
-    /** True if only scriptSigs are different */
-    bool IsEquivalentTo(const CWalletTx& tx) const;
+    /** True if tx is a malleation of this, i.e. it has the exact same version, locktime,
+     * input order, input outpoints, input sequences, and outputs. Input scriptSigs and input scriptWitnesses may differ. */
+    bool IsMalleation(const CWalletTx& tx) const;
 
     bool InMempool() const;
 

### src/wallet/wallet.cpp
@@ -753,7 +753,7 @@ std::set<CWalletTx*, WalletTxOrderComparator> CWallet::GetMalleatedVariants(cons
         if (!Assume(entry != mapWallet.end())) continue; // sanity-check: mapTxSpends has txs that are in mapWallet
         const bool is_self = &entry->second == &wtx;
         found_self |= is_self;
-        if (is_self || wtx.IsEquivalentTo(entry->second)) {
+        if (is_self || wtx.IsMalleation(entry->second)) {
             Assume(txs.insert(&entry->second).second);
         }
     }