bug: `op-node` shouldn't call `debug_chainConfig` on auth-rpc when working with custom chain configs

**Bug Description**

1. As of #14179 `op-node`, when using non-standard (non superchain) chain IDs, is trying to call `debug_chainConfig` method against _authrpc_ port of the EL.

See:

- https://github.com/ethereum-optimism/optimism/blob/v1.11.0/op-node/node/node.go#L464-L466

2. However, `debug` namespace is _not_ implemented by authrpc.

See:

- https://github.com/ethereum-optimism/op-geth/blob/v1.101500.0/node/defaults.go#L52
- https://github.com/ethereum-optimism/op-geth/blob/v1.101500.0/node/node.go#L433-L436

3. Consequently the `op-node` deterministically fails on start with something like:

```text
failed to setup: unable to create the rollup node: failed to init L2: failed to load or fetch chain config for id NNNN: fetching: Method not found
```

**Steps to Reproduce**

1. Try to use custom chain config (via `rollup.json`).

**Expected behavior**

No failure when custom chain config is used.

**Environment Information:**

- Ubuntu 24.04.1 LTS
- op-node v1.11.0

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