Configure custom RPC for the ENSNode "v2 Sepolia" instance in the Yellow env

[tk-o]

This PR requires updating the env vars for ENSIndexer "v2 Sepolia" instance to include the RPC URL for the Sepolia-fork chain. Also, the active plugins for that ENSIndexer instance must be: subgraph,unigraph,protocol-acceleration.

[coderabbitai]

🔗 Related PRs

#1575 - fix: add correct ensv1 and ensv2 addresses to sepolia-v2 namespace [merged]
#1580 - docs(ensnode): update hosted instances list [merged]
#1586 - fix: update ENSv1Registry address in ens-test-env devnet config [merged]
#1730 - Remove Core Plugin Restriction [merged]
#1822 - Disable all use of Websocket RPCs for ENSIndexer [merged]

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