Fix bug for additional Tip

[sunce86]

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

• Additional tip is always added to final estimated tip.

How to test

Will try it out on staging.

[squadgazzz]

At first glance, that looks reasonable. Can't come up with any pitfalls atm.

[MartinquaXD]

Change makes sense to me but we might as well clean up a tiny bit of tech debt here.