fix(elasticloadbalancingv2): access logging fails on imported bucket (#27948)

#27558 fixed a circular dependency issue between the bucket and the ELB when using `logAccessLogs` by adding the dependency at the L1 level.
The dependency was added on both the bucket and the bucket policy (which already refers to the bucket).

This introduced a new bug when adding a dependency for imported buckets (as `bucket.node.defaultChild` is `undefined`).

This PR fixes the issue by adding the dependency at the L1 level on the bucket policy directly.

Closes #27928.

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Author: lpizzinidev