feat: bump overhead when sending to zkSync chains (#5103)

### Description

Context:
https://discord.com/channels/935678348330434570/1319115367167033399/1319442102454849639

zkSync chains have non standard EVM gas metering, and their
eth_estimateGas RPC returns abnormally high estimates compared to the
actual usage. As a semi-temporary workaround, we bump the overhead to
result in more gas paid for. The impact of this is actually not
meaningful when it comes to cost borne by users - because the zkSync
chains are cheap, our min fee logic means that applying this still
results in a ~20c cost to users

### Drive-by changes

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Are there any minor or drive-by changes also included?
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### Related issues

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- Fixes #[issue number here]
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### Backward compatibility

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implications, e.g. changes that would prohibit deploying older commits
using this infra tooling?

Yes/No
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### Testing

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What kind of testing have these changes undergone?

None/Manual/Unit Tests
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typescript/infra/config/environments/mainnet3/igp.ts

@@ -1,6 +1,7 @@
 import {
   ChainMap,
   ChainName,
+  ChainTechnicalStack,
   HookType,
   IgpConfig,
   getTokenExchangeRateFromValues,
@@ -14,6 +15,7 @@ import {
   getOverhead,
 } from '../../../src/config/gas-oracle.js';
 import { mustGetChainNativeToken } from '../../../src/utils/utils.js';
+import { getChain } from '../../registry.js';
 
 import { ethereumChainNames } from './chains.js';
 import gasPrices from './gasPrices.json';
@@ -25,9 +27,15 @@ const tokenPrices: ChainMap<string> = rawTokenPrices;
 
 export function getOverheadWithOverrides(local: ChainName, remote: ChainName) {
   let overhead = getOverhead(local, remote, ethereumChainNames);
+  // Moonbeam gas usage can be up to 4x higher than vanilla EVM
   if (remote === 'moonbeam') {
     overhead *= 4;
   }
+  // ZkSync gas usage is different from the EVM and tends to give high
+  // estimates. We double the overhead to help account for this.
+  if (getChain(remote).technicalStack === ChainTechnicalStack.ZkSync) {
+    overhead *= 2;
+  }
   return overhead;
 }