Draft: Make epic upgrade messaging friendlier

What does this MR do?

Changes the messaging for when a user does not have access to Epics from "This feature is locked. Upgrade plan" to a single link that says "Upgrade your plan to unlock Epics".

Screenshots (strongly suggested)

Current messaging:

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
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Security

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