op-acceptance-tests: remove TestConductorLeadershipTransfer kona-node skip

## Summary

[`TestConductorLeadershipTransfer`](https://github.com/ethereum-optimism/optimism/blob/develop/op-acceptance-tests/tests/base/conductor/leadership_transfer_test.go) is skipped when the acceptance suite runs against kona-node.

The conductor preset assumes its CL is `*sysgo.OpNode` and panics when the selected CL is `*sysgo.KonaNode`.

## Required work

Generalize the conductor preset around backend-neutral CL capabilities, provide the Kona implementation, and remove the Kona skip from the leadership-transfer test.

## Acceptance criteria

- [ ] The root cause and resolution are documented.
- [ ] `TestConductorLeadershipTransfer` no longer skips when `DEVSTACK_L2CL_KIND=kona-node`.
- [ ] The same leadership-transfer behavior is exercised against real kona-node and op-node sequencers.
- [ ] Existing op-node coverage continues to pass.

## Related

- https://github.com/ethereum-optimism/optimism/issues/21903
- https://github.com/ethereum-optimism/optimism/issues/21906
- Parent inventory: https://github.com/ethereum-optimism/protocol-team/issues/101