This PR adds support for using the `slice` option in point-in-time searches. By
default, the slice query splits documents based on their Lucene ID. This
strategy is more efficient than the one used for scrolls, which is based on the
`_id` field and must iterate through the whole terms dictionary. When slicing a
search, the same point-in-time ID must be used across slices to guarantee the
partitions don't overlap or miss documents.
Closes#65740.
cdf67e0fd5