Updating descriptions of Connect app issue fields

[Jan Pöschko]

We maintain a Connect app that defines some custom fields via `jiraIssueFields` in its JSON descriptor. I noticed that, when changing the field descriptions in the JSON descriptors, the field descriptions shown in Jira issues are not actually updated – even when re-installing the app.

This seems like https://community.atlassian.com/t5/Jira-Core-Server-questions/Updated-Custom-field-description-and-values-not-updating-on/qaq-p/1664811 and https://confluence.atlassian.com/jirakb/changes-to-custom-field-descriptions-are-not-visible-on-the-create-issue-screen-in-jira-server-833986770.html – except that editing the Field Configuration doesn't work, either. It's not allowed manually nor programmatically (via the ` PUT /fieldconfiguration/{id}/fields` API), saying that "Locked fields cannot be configured."

How can a Connect app change the description of the issue fields it defines?

Also related: https://jira.atlassian.com/browse/JRASERVER-40782