SLING-3697 - Incorrect handling of deeply nested aggregates

Simplify VaultFile lookup in
VltSerializationDataBuilder.findAggregateChain

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1605440 13f79535-47bb-0310-9956-ffa450edef68
SLING-3697 - Incorrect handling of deeply nested aggregates

Downgrade a warning about no serialization data being found to a debug,
since it's now handled properly.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1605441 13f79535-47bb-0310-9956-ffa450edef68