ER_UNKNOWN_ERROR reported due to LIMIT ROWS EXAMINED

This is forked from MDEV-28613:

--source include/have_innodb.inc

--error 0,ER_UNKNOWN_ERROR

SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_INDEXES LIMIT ROWS EXAMINED 5;

The cause of this is two functions in sql/sql_show.cc. It could affect also other information_schema table plugins which return nonzero when schema_table_store_record() returns nonzero. Either that function or get_schema_tables_result() or all functions in between will need to be fixed somehow, for example, the bool error code needs to be changed to int.