When index file is larger than 4GB, offset calculation will overflow
uint32_t and _promoted_index_end will be too small.
As a result, promoted_index_size calculation will underflow and the
rest of the page will be interpretd as a promoted index.
The partitions which are in the remainder of the index page will not
be found by single-partition queries.
Data is not lost.
Introduced in 6c5f8e0eda.
Fixes#6040
Message-Id: <20200521174822.8350-1-tgrabiec@scylladb.com>
(cherry picked from commit a6c87a7b9e)
90002ca3d2