[JIRAALIGN-1064] Spliting Feature PI/Release is not reflected on assigned stories

Issue Summary

Stories under a splitted feature is displayed as misaligned stories in the program room.

Steps to Reproduce

1. Split a feature with stories and on the split dialog, set Unassigned Backlog as Targeted Release.
2. Click Split.
3. View the program in Program Room.
4. Scroll down to the bottom and you will see Misaligned Stories

Expected Results

Stories that are part of the splitted feature should also get an Unassigned PI and not a misaligned story.

Actual Results

Story's retain the PI/release of the original Feature.  

Workaround

None.