Update Gantt Chart example datasets and reflow logic to maintain consistency

[sdadn]

Story

JIRA: UXPLATFORM-5480

Description

As a developer, I would like to make changes to the example datasets and example reflow logic for Gantt Chart examples.

Motivation

So that consistency can be maintained across all the examples present in the terra-dev site.

Definition of Done

We'll know we're done when the datasets and reflow logic for Gantt Chart examples are consistent:

• Reflow logic for both react and carbon-centric examples are updated to be consistent with this logic: Updated timeline documentation and examples to be carbon centric #193 (comment)
• All datasets are updated to be non arrays
• Dedicated graph config objects are added for the examples where they are dynamically updated