Admin control for pinning the fields and clearing pinned fields

Issue Summary

When users want to pin new fields, they get the error 'Too many pinned fields'.

Currently, the number of pinned fields is limited to how much space each field's id store in api/2/mypreferences. Since this has a limit of 255 characters, depending on which fields are pinned, one user will be allowed to pin more fields than another user. Reference: JRACLOUD-78946

When the pinned fields are removed from the Issue layout, they still count towards the 255-character limit, the user doesn't have any way to unpin the hidden fields.

Steps to Reproduce

Below is a scenario that can break the pinned field limit:

• A user has 10 custom fields that were pinned, and the string length for those field ids has nearly reached the exceeding.
• Previously pinned custom fields were removed from the issue layout, so these fields are no longer shown from the issue view, but the pin field store still keeps the values and wasn't updated.
• The user pins a new field => Error occurs.

Expected Results

Users should be able to clear the hidden pinned fields or the Admin should be able to clear the pinned fields for a single user or multiple users.

(or)

Don't count the hidden pinned fields towards the 255-character limit for pinned fields.

Actual Results

No way for Admin or User to clear the hidden pinned fields 

Workaround

There is no workaround for Admin to clear the pinned fields, however, individual users can clear all the pinned fields using the API

Listing Pinned Fields:

To identify which fields are pinned by the user for the specific project, log in to Jira as the user having the issue, open the URL - https://<site URL>/rest/api/3/mypreferences?key=jira.user.issue.details.pinned-fields.<project key> in the browser.

Note: This will list all pinned fields (including the hidden pinned fields)

Resetting pinned fields:

We can reset the pinned fields set for you in this project by clearing the preferences key=jira.user.issue.details.pinned-fields, this can be done via REST API by running the command below using curl:

curl --request DELETE --url "https://<site URL>/rest/api/3/mypreferences?key=jira.user.issue.details.pinned-fields.<project key>" --user "<user mail ID>:<replace with user API token>" 

To generate an API token for your user please follow the instructions in this article. Note: The token needs to be generated from the user account having the issue.