Update mock data and fix vacuous group id check in epic roadmap

What does this MR do?

• Updates the outdated roadmap mock data (fields and type mismatches, etc).
  • In addition to ensuring the fidelity of our tests, this eases us into testing with a mocked apollo client in the future.
• Removes a small tech debt (removing unused/unnecessary utils from epic_utils.js)
• Fixes a vacuous group id check in epic_item_details.vue

Screenshot

Before	After

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