Convert Slurm job names from UTF-8 to ISO-8859-1

[jtpalmer]

Description

Updates the Slurm shredder to convert job name encoding before inserting data into the database.

Motivation and Context

If these characters are not converted it may result in database errors.

https://help.xdmod.org/a/tickets/24081

Tests performed

Added unit test.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project as found in the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.