Remove Locust from API repo

[cris-oddball]

User Story - Business Need

Once the new performance testing system is complete, we want to remove the old system.

• Ticket is understood, and QA has been contacted (if the ticket has a QA label).

User Story(ies)

As a VANotify
I want to remove API code that is no longer necessary
So that the codebase is clean and easy to maintain

Additional Info and Resources

• remove directory load_testing
• remove all GHA actions associated with Locust

Acceptance Criteria

• There are no more traces of locust in our application repo

QA Considerations

• double-check that all references to Locust no longer exists in this repo.

Potential Dependencies

Needs the new system to be working first.

[npmartin-oddball]

Hey team! Please add your planning poker estimate with Zenhub @coreycarvalho @cris-oddball @EvanParish @k-macmillan @kalbfled @MackHalliday @mchlwellman

[npmartin-oddball]

Still needed.