[12.x] Remove unused catch variable in Job::fail()

[sumaiazaman]

This PR removes an unused exception variable in a catch block that only contains a comment.

Changes:

• Removes unused $e parameter from catch block in Job::fail() method
• Uses PHP 8.0+ syntax to omit the variable name when the caught exception is not used

Benefits:

• Cleaner code following modern PHP practices
• Eliminates unused variable warnings in static analysis tools
• Consistent with similar changes in Laravel framework (see [12.x] Refactor: remove un use var #57617)

Testing:

• Existing tests continue to pass
• No functional changes to exception handling behavior