Clean up SegmentLineage#toJsonObject and change listSegmentLineage to reversed chronological order.

As a follow up to https://github.com/apache/pinot/issues/9005, refactor `SegmentLineage#toJsonObject` by moving the sorting logic out to keep `toJsonObject` lightweight and in line with proper convention.
Also, change `PinotSegmentRestletResource#listSegmentLineage` to return entries in reversed chronological order instead.

Start by reading SegmentLineage#toJsonObject and PinotSegmentRestletResource#listSegmentLineage, along with the follow-up issue 9005. Trace where sorting currently occurs and how lineage entries are assembled; done means toJsonObject no longer performs sorting and the REST resource returns entries in reversed chronological order.

Written by the indexing model from the issue text.