Refactor setter methods in `TestingEventBuilder`

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## 👾 Description of the issue

The `TestingEventBuilder` class has many setter methods that return `this`. Such methods are usually named `withThisValue()` instead of `setThisValue()` because methods that start with `set` should be simple void setters. This ticket is to refactor all `set` methods in `TestingEventBuilder` to `with` methods.

### Steps to reproduce

See the `TestingEventBuilder.java` class. Observe the set methods that return `this`.

### Proposed Solution:

Refactor the `set` methods to `with`. Example: `setTimeCreated(...)` should be refactored to `withTimeCreated(...)`. All other aspects of the method definition should remain unchanged.

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Start with the TestingEventBuilder.java class and identify every set method that returns this. Rename those methods to with equivalents, such as setTimeCreated to withTimeCreated, while leaving the other method details unchanged; done means all such setter methods have been refactored consistently.

Written by the indexing model from the issue text.