fix: do not remove assignment when closed (#17613)

diff --git a/erpnext/support/doctype/issue/issue.py b/erpnext/support/doctype/issue/issue.py
index d626def..dca06d4 100644
--- a/erpnext/support/doctype/issue/issue.py
+++ b/erpnext/support/doctype/issue/issue.py
@@ -32,10 +32,6 @@
 		self.update_status()
 		self.set_lead_contact(self.raised_by)
 
-		if self.status == "Closed":
-			from frappe.desk.form.assign_to import clear
-			clear(self.doctype, self.name)
-
 	def on_update(self):
 		# Add a communication in the issue timeline
 		if self.flags.create_communication and self.via_customer_portal: