[JIRAALIGN-1917] Parent Epic or Capability: Accepted Parent Object is Removed From Child Feature Parent Object Drop Down

Issue Summary

When user accepts a parent object before the children are accepted, this nulls the parent object dropdown. This causes issues for some customers due to them having the parent object field required, so they can't make changes to the feature work item unless they select a new parent object or change the state of the parent back to in progress (or not started). 

Steps to Reproduce

1. Step 1 - Navigate to a parent object (Epic or Capability)
2. Step 2 - Accept the parent object
3. Step 3 - Navigate to the associate child item that is still active
4. Step 4 - Notice the parent object dropdown value is Null

Expected Results

Per kforeman@atlassian.com: The capability should be retained in the dropdown even if accepted. If the users changes the parent, then save the feature, then the accepted capability should not show. However, it should be retained until the user changes/saves

Actual Results

Nulls the dropdown value

Workaround

No workaround