fix: use correct size for databus_id (#10673)

Apparently at the time the below issue was created things failed if we
used the correct limited size for the databus_id poly. Maybe we made a
mistake then or maybe something got fixed somewhere but either way it
works fine now.

Closes AztecProtocol/barretenberg#1107

barretenberg/cpp/src/barretenberg/ultra_honk/decider_proving_key.hpp

@@ -177,11 +177,7 @@ template <IsUltraFlavor Flavor> class DeciderProvingKey_ {
                     proving_key.polynomials.return_data_read_tags =
                         Polynomial(MAX_DATABUS_SIZE, proving_key.circuit_size);
 
-                    // TODO(https://github.com/AztecProtocol/barretenberg/issues/1107): Restricting databus_id to
-                    // databus_size leads to failure.
-                    // const size_t databus_size = std::max({ calldata.size(), secondary_calldata.size(),
-                    // return_data.size() });
-                    proving_key.polynomials.databus_id = Polynomial(proving_key.circuit_size, proving_key.circuit_size);
+                    proving_key.polynomials.databus_id = Polynomial(MAX_DATABUS_SIZE, proving_key.circuit_size);
                 }
                 const size_t max_tables_size =
                     std::min(static_cast<size_t>(MAX_LOOKUP_TABLES_SIZE), dyadic_circuit_size - 1);