chore: Rollback after each test, due to premature commit via remove_user_permission (backport #29964) (#29967)

* chore: Rollback after each test, due to premature commit via `remove_user_permission`

- `remove_user_permission` in `test_warehouse_user` calls delete_doc that enqueues dynamic link deletion
- Execution of background job eventually commits
- While in the test suite it runs sequentially in the same thread and commits whatever was done until then
- Which is why the rollback in `tearDownClass` is quite useless here
- This premature commit causes many illegal transactions caught by `assertRaises` to be committed in the db
- This creates faulty/dirty ledgers and breaks reports, as outiside the test suite this shouldn't/wouldn't happen
- Rollback after each test, and for `test_warehouse_user` in particular, manually cancel transaction

(cherry picked from commit bf8743713d)

# Conflicts:
#	erpnext/stock/doctype/stock_entry/test_stock_entry.py

* test: Make Variant if absent in `test_variant_work_order`, keep test atomic

(cherry picked from commit 5ff3705872)

* fix: Merge conflicts

Co-authored-by: marination <maricadsouza221197@gmail.com>

erpnext/stock/doctype/stock_entry/test_stock_entry.py

@@ -45,6 +45,7 @@ def get_sle(**args):
 
 class TestStockEntry(ERPNextTestCase):
 	def tearDown(self):
+		frappe.db.rollback()
 		frappe.set_user("Administrator")
 		frappe.db.set_value("Manufacturing Settings", None, "material_consumption", "0")
 
@@ -566,6 +567,7 @@ class TestStockEntry(ERPNextTestCase):
 		st1.set_stock_entry_type()
 		st1.insert()
 		st1.submit()
+		st1.cancel()
 
 		frappe.set_user("Administrator")
 		remove_user_permission("Warehouse", "_Test Warehouse 1 - _TC", "test@example.com")
@@ -690,6 +692,8 @@ class TestStockEntry(ERPNextTestCase):
 		bom_no = frappe.db.get_value("BOM", {"item": "_Test Variant Item",
 			"is_default": 1, "docstatus": 1})
 
+		make_item_variant() # make variant of _Test Variant Item if absent
+
 		work_order = frappe.new_doc("Work Order")
 		work_order.update({
 			"company": "_Test Company",
@@ -1101,13 +1105,10 @@ class TestStockEntry(ERPNextTestCase):
 
 		# Check if FG cost is calculated based on RM total cost
 		# RM total cost = 200, FG rate = 200/4(FG qty) =  50
-		self.assertEqual(se.items[1].basic_rate, 50)
+		self.assertEqual(se.items[1].basic_rate, flt(se.items[0].basic_rate/4))
 		self.assertEqual(se.value_difference, 0.0)
 		self.assertEqual(se.total_incoming_value, se.total_outgoing_value)
 
-		# teardown
-		se.delete()
-
 def make_serialized_item(**args):
 	args = frappe._dict(args)
 	se = frappe.copy_doc(test_records[0])