wallet, spend: Remove fWatchOnly from CCoinControl

Descriptor wallets do not have a concept of watchonly within a wallet,
so remove the watchonly option from coin control.

src/wallet/coincontrol.h

@@ -89,8 +89,6 @@ public:
     //! If true, the selection process can add extra unselected inputs from the wallet
     //! while requires all selected inputs be used
     bool m_allow_other_inputs = true;
-    //! Includes watch only addresses which are solvable
-    bool fAllowWatchOnly = false;
     //! Override automatic min/max checks on fee, m_feerate must be set if true
     bool fOverrideFeeRate = false;
     //! Override the wallet's m_pay_tx_fee if set

src/wallet/rpc/spend.cpp

@@ -1067,7 +1067,6 @@ static RPCHelpMan bumpfee_helper(std::string method_name)
     Txid hash{Txid::FromUint256(ParseHashV(request.params[0], "txid"))};
 
     CCoinControl coin_control;
-    coin_control.fAllowWatchOnly = pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
     // optional parameters
     coin_control.m_signal_bip125_rbf = true;
     std::vector<CTxOut> outputs;

src/wallet/spend.cpp

@@ -54,7 +54,7 @@ static bool IsSegwit(const Descriptor& desc) {
 static bool UseMaxSig(const std::optional<CTxIn>& txin, const CCoinControl* coin_control) {
     // Use max sig if watch only inputs were used or if this particular input is an external input
     // to ensure a sufficient fee is attained for the requested feerate.
-    return coin_control && (coin_control->fAllowWatchOnly || (txin && coin_control->IsExternalSelected(txin->prevout)));
+    return coin_control && txin && coin_control->IsExternalSelected(txin->prevout);
 }
 
 /** Get the size of an input (in witness units) once it's signed.
@@ -429,7 +429,7 @@ CoinsResult AvailableCoins(const CWallet& wallet,
         // Because CalculateMaximumSignedInputSize infers a solvable descriptor to get the satisfaction size,
         // it is safe to assume that this input is solvable if input_bytes is greater than -1.
         bool solvable = input_bytes > -1;
-        bool spendable = ((mine & ISMINE_SPENDABLE) != ISMINE_NO) || (((mine & ISMINE_WATCH_ONLY) != ISMINE_NO) && (coinControl && coinControl->fAllowWatchOnly && solvable));
+        bool spendable = (mine & ISMINE_SPENDABLE) != ISMINE_NO;
 
         // Filter by spendable outputs only
         if (!spendable && params.only_spendable) continue;