fix: Media library folders and files can get unintentionally deleted

[Marc-Roig]

What does it do?

Delete folder logic was doing something like:

 await strapi.db.query(FILE_MODEL_UID).findMany({
    where: { folderPath: { $startsWith: path } },
  });

And we were missing an edge case. In a list of folder paths like:

/1
/2
/3
/10

If you want to delete /1, and you match by doing { $startsWith: "/1" }, you would get /1 but also /10.

This PR improves the query to prevent this behaviour.

Related issue(s)/PR(s)

Fixes #16734