fix: align engine RPC protocols between mainnet and sepolia configs

[Kewe63]

Summary

Aligns the Sepolia engine RPC protocols with the Mainnet configuration for consistency.

Problem

The Sepolia configuration had OP_NODE_L2_ENGINE_RPC as ws:// and BASE_NODE_L2_ENGINE_RPC as http://, which was the inverse of the Mainnet setup. This inconsistency could lead to confusion and potential health-check derivation failures.

Solution

• Swapped OP_NODE_L2_ENGINE_RPC to http://.
• Swapped BASE_NODE_L2_ENGINE_RPC to ws://.

Verification

• Verified that the protocol swap matches the documented Mainnet pattern.
• Ensured health-check URL derivation works correctly.

Impact

Improves configuration consistency across environments.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	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 1 Sum 2