Call ds.close() in more places in tests

Refs #2692

tests/test_api_write.py

@@ -22,12 +22,7 @@ def ds_write(tmp_path_factory):
     ds = Datasette([db_path], immutables=[db_path_immutable])
     ds.root_enabled = True
     yield ds
-    # Close both setup connections plus any Datasette-managed connections.
-    db1.close()
-    db2.close()
-    for database in ds.databases.values():
-        if not database.is_memory:
-            database.close()
+    ds.close()
 
 
 def write_token(ds, actor_id="root", permissions=None):