Add the OP_NODE_L1_BEACON flag

[fala13]

Flag OP_NODE_L1_BEACON was introduced to Optimism in:
ethereum-optimism/optimism#9120

Base already has it in .env:
https://github.com/base-org/node/releases/tag/v0.7.1

(and maybe bump to op-node docker v.1.5.1 while updating).

[Chomtana]

Thanks, flag already added and bumped on the recent merge