fix(gateway): address SonarQube PR-mode findings on F2/F3 code

- data_sink.py: _IDENTIFIER_RE uses \w+/re.ASCII instead of the
  equivalent-but-verbose [A-Za-z0-9_]+ character class (verified same
  match behavior). NOSONAR on update_write_status's 'async with no
  await inside' - deliberate, per the ponytail comment already in the
  method body (uniform async interface across DataSink, no async pg driver).
- test_grpc_server.py: move make_request() out of the pytest.raises
  block so exactly one call can raise the expected exception.
- sonar-project.properties: exclude ingestor/proto/ (generated grpc
  code) from analysis - its ReadTag/etc. names are dictated by
  grpcio-tools, not a style choice, and renaming them breaks the wire.

tests/unit/adapters/test_grpc_server.py

@@ -60,8 +60,9 @@ async def test_read_tag_aborts_with_internal_on_engine_failure():
     context = AsyncMock()
     context.abort.side_effect = grpc.RpcError('aborted')
 
+    request = make_request()
     with pytest.raises(grpc.RpcError):
-        await servicer.ReadTag(make_request(), context)
+        await servicer.ReadTag(request, context)
 
     context.abort.assert_awaited_once()
     args = context.abort.call_args.args