Tool cleanup_mri_tables_for_19-0_release.php prompting for MySQL username and password

[cmadjar]

This pull request modifies the way the mysqldump is called in cleanup_mri_tables_for_19-0_release.php.

Instead of using the username and password from the config.xml file, it will prompt the user running the script to enter the MySQL username and password to use for mysqldump.

[ridz1208]

it works!! but i'm having a separate issue now.

The script outputs the file in the directory where its being run from
it should instead add the file to a specific directory such as project/backup/ which would be created if it does not exist

should be a separate PR