Remove block information from description of some WAL records for GIN

Remove block information from description of some WAL records for GIN

The WAL records XLOG_GIN_INSERT and XLOG_GIN_VACUUM_DATA_LEAF_PAGE
included some information about the blocks added to the record.

This information is already provided by XLogRecGetBlockRefInfo() with
much more details about the blocks included in each record, like the
compression information, for example.  This commit removes the block
information that existed in the record descriptions specific to GIN.

Author: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CALdSSPgk=9WRoXhZy5fdk+T1hiau7qbL_vn94w_L1N=gtEdbsg@mail.gmail.com