In commit fa8a46eb (MDEV-33613)
the parameter innodb_lru_flush_size ceased to have any effect.

Let us declare the parameter as deprecated and additionally as
MARIADB_REMOVED_OPTION, so that there will be a warning written
to the error log in case the option is specified in the command line.

Let us also do the same for the parameter
innodb_purge_rseg_truncate_frequency
that was deprecated&ignored earlier in MDEV-32050.

Reviewed by: Debarun Banerjee