Sim mode submit num fix

[MetRonnie]

Fixes small bug in simulation mode where the submit_num in the task_states table would not be updated from 0 to 1 when the task goes from waiting -> running -> succeeded.

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• No dependency changes
• Tests are included
• Changelog entry included if this is a change that can affect users
• No docs needed
• If this is a bug fix, PR should be raised against the relevant ?.?.x branch.