Also change config patching

src/cluster.py

@@ -846,7 +846,7 @@ def update_synchronous_node_count(self, units: int | None = None) -> None:
             with attempt:
                 r = requests.patch(
                     f"{self._patroni_url}/config",
-                    json={"synchronous_node_count": units // 2},
+                    json={"synchronous_node_count": units - 1},
                     verify=self.verify,
                     auth=self._patroni_auth,
                     timeout=PATRONI_TIMEOUT,

tests/integration/helpers.py

@@ -1043,15 +1043,14 @@ def switchover(
     )
     assert response.status_code == 200
     app_name = current_primary.split("/")[0]
-    minority_count = len(ops_test.model.applications[app_name].units) // 2
     for attempt in Retrying(stop=stop_after_attempt(30), wait=wait_fixed(2), reraise=True):
         with attempt:
             response = requests.get(f"http://{primary_ip}:8008/cluster")
             assert response.status_code == 200
             standbys = len([
                 member for member in response.json()["members"] if member["role"] == "sync_standby"
             ])
-            assert standbys >= minority_count
+            assert standbys == len(ops_test.model.applications[app_name].units) - 1
 
 
 async def wait_for_idle_on_blocked(