TRUNK-6450: Deleting a role with a parent temporarily breaks some parts of the application

[shivvani-r]

Description of what I changed

This PR fixes a caching issue where deleting a Child Role left the Parent Role with a stale reference to the deleted child in its childRoles collection. This caused UI breakages when trying to view the Parent Role immediately after deletion.

I modified UserServiceImpl.purgeRole() to fix a cache incoherency where a parent role retains a stale reference to a deleted child role.

Changes:

• The Fix: Before purging a child role, the method now iterates through all its parent roles, removes the child from their collections, and saves the parent. This forces the Hibernate cache to update immediately.
• The Test: Added a regression test purgeRole_shouldUpdateParentRoleCacheWhenChildRoleIsDeleted in UserServiceTest to verify that the parent's child collection is empty after the delete.

Issue I worked on

see https://issues.openmrs.org/browse/TRUNK-6450

Checklist: I completed these to help reviewers :)

• My IDE is configured to follow the code style of this project.

• I have added tests to cover my changes.

• I ran mvn clean package right before creating this pull request and added all formatting changes to my commit.

• All new and existing tests passed.

• My pull request is based on the latest changes of the master branch.

[dkayiwa]

Can you discard the formatting changes?

[shivvani-r]

@dkayiwa i deleted the commit with the formatting changes.