Fix the worker run test

Description

Fixes the worker#run test failing sometimes because of race conditions.

Changes

Changes the worker test so it mocks out threading.

Additions

Adds a new method to the Threads helper that spawns un-managed threads.

Test and Review

To be filled in by the reviewers

• All of the methods are commented to expectation

• The methods are tested to satisfaction

• There are no unnecessary files present in the MR

• The continuous integration has no problems with the MR

• The MR is filled in as requested (including labels, milestones, and reviewers)

• The documentation is up-to-date

• All nullable parameters are marked as such