Fix bug for additional Tip (#3311)

# Description
I've noticed that non-colocated drivers almost always have `tip` = 1
gwei, even in volatile periods when base fee raises significantly.

The reason is, our first choice gas price estimator almost always
returns tip < 1 gwei, so the `self.min_priority_fee` is always used as a
tip and it's fixed. (The reason why gas price estimator always return
tip <1 gwei will be analyzed independently of this fix, but one of the
reasons can be: using default inclusion time of 30s always, estimating
gas price at the SOLVE time instead of SETTLE time etc, or just not
working properly).

This PR makes the tip always dependable of `additionalTip` config that
is used by infra to additionally tweak gas price estimations if needed.

# Changes
<!-- List of detailed changes (how the change is accomplished) -->

- [ ] Additional tip is always added to final estimated tip.

## How to test
Will try it out on staging.

<!--
## Related Issues

Fixes #
-->

crates/driver/src/infra/blockchain/gas.rs

@@ -4,8 +4,10 @@
 /// private submission networks are used.
 use {
     super::Error,
-    crate::infra::config::file::GasEstimatorType,
-    crate::{domain::eth, infra::mempool},
+    crate::{
+        domain::eth,
+        infra::{config::file::GasEstimatorType, mempool},
+    },
     ethcontract::dyns::DynWeb3,
     gas_estimation::{GasPriceEstimating, nativegasestimator::NativeGasEstimator},
     std::sync::Arc,
@@ -18,7 +20,7 @@ type AdditionalTip = (MaxAdditionalTip, AdditionalTipPercentage);
 pub struct GasPriceEstimator {
     //TODO: remove visibility once boundary is removed
     pub(super) gas: Arc<dyn GasPriceEstimating>,
-    additional_tip: Option<AdditionalTip>,
+    additional_tip: AdditionalTip,
     max_fee_per_gas: eth::U256,
     min_priority_fee: eth::U256,
 }
@@ -51,7 +53,8 @@ impl GasPriceEstimator {
                     ..
                 } => (max_additional_tip, additional_tip_percentage),
             })
-            .next();
+            .next()
+            .unwrap_or((eth::U256::zero(), 0.));
         // Use the lowest max_fee_per_gas of all mempools as the max_fee_per_gas
         let max_fee_per_gas = mempools
             .iter()
@@ -81,24 +84,20 @@ impl GasPriceEstimator {
         self.gas
             .estimate()
             .await
-            .map(|mut estimate| {
-                let estimate = match self.additional_tip {
-                    Some((max_additional_tip, additional_tip_percentage)) => {
-                        let additional_tip = max_additional_tip
-                            .to_f64_lossy()
-                            .min(estimate.max_fee_per_gas * additional_tip_percentage);
-                        estimate.max_fee_per_gas += additional_tip;
-                        estimate.max_priority_fee_per_gas += additional_tip;
-                        estimate
-                    }
-                    None => estimate,
-                };
+            .map(|estimate| {
+                let (max, percentage) = self.additional_tip;
+                let additional_tip = max
+                    .to_f64_lossy()
+                    .min(estimate.max_fee_per_gas * percentage);
+
+                let tip = std::cmp::max(
+                    self.min_priority_fee + eth::U256::from_f64_lossy(additional_tip),
+                    eth::U256::from_f64_lossy(estimate.max_priority_fee_per_gas + additional_tip),
+                );
+
                 eth::GasPrice::new(
                     self.max_fee_per_gas.into(),
-                    std::cmp::max(
-                        self.min_priority_fee.into(),
-                        eth::U256::from_f64_lossy(estimate.max_priority_fee_per_gas).into(),
-                    ),
+                    tip.into(),
                     eth::U256::from_f64_lossy(estimate.base_fee_per_gas).into(),
                 )
             })