Open-event-frontend: Creation of New Order Fails

[CosmicCoder96]

Describe the bug

When the user selects the available tickets for an event and proceeds to place an order, the creation fails. The server raises a 422: Unprocessable Entity.

The 422 is caused due to the missing attendees relationship in the POST request data sent to the server. However, intriguingly, the error disappears, if the order relationship defined in the attendee model defined as order: belongsTo: ('order') is removed.

Upon removal of the relationship from the model, Ember automatically starts including attendees in the POST request.

[CosmicCoder96]

While PR #1752 may serve as a temporary fix, we require some help in identifying the root cause of this behavior.
@niranjan94 @pradeepgangwar @ritikamotwani @Anupam-dagar @shreyanshdwivedi

[CosmicCoder96]

Order creations seems stable so far in the test run. Can be reopened later if issues are encountered.