fix: update multicall with .env.bridge file

[lesterli]

Summary

This PR updates the scripts under l2-bridge to fix an issue:

Updating .env.bridge file for OP Bridge UI...
/home/snapchain/op-chain-deployment/scripts/l2-bridge/l2-bridge-set-env.sh: line 37: NEXT_PUBLIC_L1_MULTICALL3_ADDRESS: unbound variable
make[1]: *** [Makefile:86: l2-bridge-start] Error 1

we removed NEXT_PUBLIC_L1_MULTICALL3_ADDRESS from the .env file, so:

• l2-bridge-deploy-l1-multicall.sh: for the multicall was deployed case, it should update.env.bridge;
• l2-bridge-set-env.sh: remove replacement line for NEXT_PUBLIC_L1_MULTICALL3_ADDRESS

Updates: Also, it will add two env vars for bridge ui.

Test Plan

To change the L1_RPC_URL with the Sepolia, run:

make l2-bridge-deploy-l1-multicall 

it should update NEXT_PUBLIC_L1_MULTICALL3_ADDRESS in .env.bridge with the value 0xcA11bde05977b3631167028862bE2a173976CA11

[bap2pecs]

lgtm