tests: wait for the victim node to apply the dirty offset

Controller erasure test is supposed to validate if there is a mismatch
between the last appended entry in kvstore and controller max offset. In
order for the test to work correctly we must wait for all the messages
to be committed as we only delete the last segment that contains a
single message (new replicated configuration). In order to make the test
reliable change the condition to wait for the applied offset on the node
where controller log is going to be removed to be equal to the leader
dirty offset.

Fixes: #8217

Signed-off-by: Michal Maslanka <michal@redpanda.com>

tests/rptest/tests/controller_erase_test.py

@@ -57,7 +57,7 @@ def test_erase_controller_log(self, partial):
 
         # Stop the node we will intentionally damage
         victim_node = self.redpanda.nodes[1]
-        bystander_node = self.redpanda.nodes[0]
+        bystander_node = self.redpanda.controller()
 
         def wait_all_segments():
             storage = self.redpanda.node_storage(victim_node)
@@ -75,20 +75,19 @@ def wait_all_segments():
             f"Victim node({victim_node}) does not contain expected segments count({transfers_leadership_count + 1}) for controller log"
         )
 
-        bystander_node_last_applied_offset = admin.get_controller_status(
-            bystander_node)["last_applied_offset"]
+        bystander_node_dirty_offset = admin.get_controller_status(
+            bystander_node)["dirty_offset"]
 
         def wait_victim_node_apply_segments():
             return admin.get_controller_status(victim_node)[
-                "last_applied_offset"] >= bystander_node_last_applied_offset
+                "last_applied_offset"] >= bystander_node_dirty_offset
 
         wait_until(
             wait_victim_node_apply_segments,
             timeout_sec=40,
             backoff_sec=1,
             err_msg=
-            f"Victim node did not apply {bystander_node_last_applied_offset} offset"
-        )
+            f"Victim node did not apply {bystander_node_dirty_offset} offset")
 
         self.redpanda.stop_node(victim_node)