chore(L1): remove EthLockbox

[jackchuma]

What changed? Why?

Removed the unused EthLockbox contract and all of its integration points. OptimismPortal2 now keeps ETH directly, while retaining the former storage slot as a generic spacer for upgrade compatibility.

Notes to reviewers

• Removes EthLockbox deployment artifacts, feature-flag handling, portal calls, tests, and snapshots.
• Updates portal and bridge custody assertions to expect ETH to remain in OptimismPortal2.

How has it been tested?

• forge build --skip "/**/test/**" --skip "/**/scripts/**"
• forge test --match-path test/L1/OptimismPortal2.t.sol
• forge test --match-path test/L1/L1StandardBridge.t.sol
• forge test --match-path test/L1/SystemConfig.t.sol
• forge test --match-path test/deploy/SystemDeploy.t.sol
• forge test --match-path test/vendor/Initializable.t.sol

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[cb-heimdall]

Review Error for CatfishbillyIII @ 2026-07-21 18:31:00 UTC
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