Prioritize server-provided error messages to present to users when Jira Issues list fails

What does this MR do?

In preparation for backend work in #323304 (closed), this MR updates the Jira Issues list to use the backend-provided error message to present to the user. If no error message is present, a generic message is used.

Current possible server-provided error messages:

• An error occurred while requesting data from the Jira service.
• Jira service not configured.
• Jira project key is not configured.

Fallback error message: An error occurred while loading issues

Screenshots (strongly suggested)

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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