MDEV-6456: Add progress indication for "Reading tablespace information from the .ibd files"

# of processed files is printed every 15 sec.
Added default_role column to mysql_system_tables
Added extra error messages for default role.

Also fixed wording on one message.
Added default role implementation
Fixed comment.
Extended create_and_drop_role_invalid_user_table

Added extra check for default_role column.
Changed set_default_role_for test to clean up correctly
cleanup and updated test results