Multiparser misses files from quick simulations

[wk9874]

Describe the bug
In cases where a simulation completes so quickly and sets the termination trigger for the Multiparser before it has had a chance to start up (mostly seen on CI)

To Reproduce

• Start a process which creates an output file and then immediately stops, and sets completion trigger
• Add a small sleep
• Start file monitor

Expected behavior
File monitor should pick up files created by process and parse them

Environment (please complete the following information):

• OS: Ubuntu 24.04
• Python version: 3.12