TWSD-1307 : When we try to delete the policy then it should not delete when there is real service, virtual service or real service group is attached.
It should allow us to delete when there is no services attached to policy.

Ticket ID is - (TWSD-1307)
Issue: Policies were getting deleted even when they were still attached to Virtual service or Real service group.
Fix: Added Validation logic before deletion of policy to check weather the policy attached with virtual service or real service group.
Changes: Added validation logic in the following functions.

1)no_slb_policy_filetype_kern

2)no_slb_policy_generic_kern

3)no_slb_policy_deffault_kern

4)no_slb_policy_doh_kern

5)no_slb_policy_static_kern

6)no_slb_policy_backup_kern
Testing results were added to verify policy deletion prevented when virtual service and real service groups were added.