issues #81: Resolve database schema issue

[ScottVerbeek]

Noticed the current id column has been used a foreign key. This caused a database schema error. Below you can see the before and after upgrade results.

root@2886180ea26f:/var/www/vanilla-401# php admin/cli/check_database_schema.php 
-------------------------------------------------------------------------------
block_grade_me
 * Missing index 'id' (not unique (id)). 
CREATE INDEX mdl_blocgradme_id_ix ON mdl_block_grade_me (id);
-------------------------------------------------------------------------------
root@2886180ea26f:/var/www/vanilla-401# php admin/cli/upgrade.php 
== Upgrading Moodle database from version 4.1.8 (Build: 20231222) (2022112808) to 4.1.8 (Build: 20231222) (2022112808) ==

Your Moodle files have been changed, and you are about to automatically
upgrade your server to this version:

4.1.8 (BUILD: 20231222) (2022112808)

Once you do this you can not go back again. Please note that this process
can take a long time.

Are you sure you want to upgrade this server to this version?

type y (means yes) or n (means no)
: y
-->block_grade_me
++ 2024013100: Success (0.09 seconds) ++
++ Success (0.16 seconds) ++
-->upgrade_noncore()
++ Success (0.39 seconds) ++
== Setting new default values ==
Command line upgrade from 4.1.8 (Build: 20231222) (2022112808) to 4.1.8 (Build: 20231222) (2022112808) completed successfully.
root@2886180ea26f:/var/www/vanilla-401# php admin/cli/check_database_schema.php 
Database structure is ok.