fix: use eth_maxPriorityFeePerGas for determing gas

Update `getFeeData` to match the `ethers` algorithm, specifically don't
just assume `1_000_000_000n` as the `maxPriorityFeePerGas`. Instead call
`eth_maxPriorityFeePerGas`, and only fall back to `1_000_000_000n`, if
there is no response.

Fixes #5093

.changeset/smart-hotels-fold.md

@@ -0,0 +1,5 @@
+---
+"@nomicfoundation/hardhat-ethers": patch
+---
+
+Leverage `eth_maxPriorityFeePerGas` for the max fee per gas calculation

packages/hardhat-ethers/src/internal/hardhat-ethers-provider.ts

@@ -153,7 +153,13 @@ export class HardhatEthersProvider implements ethers.Provider {
     const latestBlock = await this.getBlock("latest");
     const baseFeePerGas = latestBlock?.baseFeePerGas;
     if (baseFeePerGas !== undefined && baseFeePerGas !== null) {
-      maxPriorityFeePerGas = 1_000_000_000n;
+      try {
+        maxPriorityFeePerGas = await this._hardhatProvider.send(
+          "eth_maxPriorityFeePerGas"
+        );
+      } catch {}
+
+      maxPriorityFeePerGas = maxPriorityFeePerGas ?? 1_000_000_000n;
       maxFeePerGas = 2n * baseFeePerGas + maxPriorityFeePerGas;
     }