Merge bitcoin/bitcoin#29076: fuzz: set m_fallback_fee and m_fee_mode in wallet_fees target

e03d6f7 fuzz: set `m_fallback_fee`/`m_fee_mode` in `wallet_fees` target (brunoerg)

Pull request description:

  `m_fallback_fee` and `m_fee_mode` are used in `GetMinimumFeeRate` but we're not setting any value for them in `wallet_fees` target. That's the reason fuzzing is never reaching the following code:

  ![Screenshot 2023-12-13 at 15 04 30](https://github.com/bitcoin/bitcoin/assets/19480819/454ddcaa-75ca-452f-ad13-5f142de0bdce)

  This PR fixes it.

ACKs for top commit:
  maflcko:
    review ACK e03d6f7
  achow101:
    ACK e03d6f7
  murchandamus:
    ACK e03d6f7

Tree-SHA512: 5d364f5351d65762a3ddf88e3abb7bda401b7e4955285e083031d216fb50082b1ea98e2c065aff75a5a8a3d1bc4c2e5e3ca9f9478d902ee8f8d4347b6cbe53af

Author: achow101

src/wallet/test/fuzz/fees.cpp

@@ -36,6 +36,10 @@ FUZZ_TARGET(wallet_fees, .init = initialize_setup)
         wallet.SetLastBlockProcessed(chainstate->m_chain.Height(), chainstate->m_chain.Tip()->GetBlockHash());
     }
 
+    if (fuzzed_data_provider.ConsumeBool()) {
+        wallet.m_fallback_fee = CFeeRate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
+    }
+
     if (fuzzed_data_provider.ConsumeBool()) {
         wallet.m_discard_rate = CFeeRate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
     }
@@ -58,6 +62,9 @@ FUZZ_TARGET(wallet_fees, .init = initialize_setup)
     if (fuzzed_data_provider.ConsumeBool()) {
         coin_control.m_confirm_target = fuzzed_data_provider.ConsumeIntegralInRange<unsigned int>(0, 999'000);
     }
+    if (fuzzed_data_provider.ConsumeBool()) {
+        coin_control.m_fee_mode = fuzzed_data_provider.ConsumeBool() ? FeeEstimateMode::CONSERVATIVE : FeeEstimateMode::ECONOMICAL;
+    }
 
     FeeCalculation fee_calculation;
     FeeCalculation* maybe_fee_calculation{fuzzed_data_provider.ConsumeBool() ? nullptr : &fee_calculation};