Remove unused variable assignment

The variable is conditionally assigned toward the end of the loop and
not used after.  It's then set back to its default value at the beginning
of the loop.

src/wallet/coinselection.cpp

@@ -478,7 +478,6 @@ util::Result<SelectionResult> CoinGrinder(std::vector<OutputGroup>& utxo_pool, c
             // Neither adding to the current selection nor exploring the omission branch of the last selected UTXO can
             // find any solutions. Redirect to exploring the Omission branch of the penultimate selected UTXO (i.e.
             // set `next_utxo` to one after the penultimate selected, then deselect the last two selected UTXOs)
-            should_cut = false;
             deselect_last();
             should_shift  = true;
         }