Excerpt extraction from the Lucene index should be more selective

Lucene index can be used in order to extract rep:excerpt using Highlighter.
The current implementation may suffer performance issues when the result set of the original query contains a lot of results, each of them possibly containing lots of (stored) properties that get passed to the highlighter in order to try to extract the excerpt; such a process doesn't stop as soon as the first excerpt is found so that excerpt is composed using text from all stored properties in all results (if there's a match on the query).

While we can accept some cost of extracting excerpt at query time (whereas it was generated at excerpt retrieval time before OAK-3580, e.g. via row.getValue("rep:excerpt")) , that should be bounded and mitigated as much as possible.