ALTER TABLE IMPORT TABLESPACE does not allow import into another schema

mariabdb-backup --prepare --export marks all InnoDB tables for export.

One problem is that one cannot import a exported table to a schema with another name than the original. This would be useful when one wants to import an old backup of a table to another schema to compare it the current table.

The reason for this is that the *.cfg files includes the schema name and the table name
and ALTER TABLE ... IMPORT TABLESPACE gives an error if the schema differs.

The suggestion is to change the error to a warning and allow the import.
This should be done in an early MariaDB version to allow restore tools to take advantage of this change with all active MariaDB versions.