Change the "Parent Link" search keyword so it doesn't conflict with the "Parent Link" custom field

Current behavior

Searching for_ Parent Link _actually searches for the CONCEPT of Parent Link, meaning it considers all three possible links:

• Issues (subtasks) with parent issues
• Issues with Epics
• Issues with Parent Links (the JPO custom field itself)

The issue

Parent Link is the name of a Portfolio for Jira (JPO) custom field.
Parent Link is also a searchable field in JQL, but it behaves differently than just searching for the Parent Link custom field, leading many users to confusion and the impression that Parent Link JQL does not work with EMPTY keyword (JPOSERVER-2477).

So if you'd want to search for issues with only the Parent Link custom field, you'd have to exclude the other 2 possible link types:

"Parent Link" is not EMPTY AND "Epic Link" is EMPTY AND issuetype in standardIssueTypes()

The ask

Make it so — somehow — that the abstraction of Parent Link search doesn't conflict with the Parent Link custom field.