Please address the comments from this code review:

## Overall Comments
- In `SendSensorACK` you pass `ctx` into `injector.InjectMessage`, but the mocks (and `common.MessageInjector` in the rest of the codebase) expect a `concurrency.Waitable` argument; consider using a proper `Waitable` (e.g. a no-op signal) instead of `context.Context` to keep the call signature consistent and avoid compilation or runtime issues.
- The behavior of `SendSensorACK` for injectors that do not implement `capabilityChecker` contradicts the comment about only sending when `SensorACKSupport` is advertised; either gate those calls as well or update the comment/tests to make the intended behavior for older/non-capability-aware injectors explicit.
- Importing `vmindexpipeline` into `connection_impl.go` to call `SendSensorACK` creates a cross-layer dependency from the generic connection layer into a specific pipeline; consider moving the ACK helper to a more neutral package (e.g. `pipeline/common` or a utility package) to keep the layering between connection and individual pipelines cleaner.

## Individual Comments

### Comment 1
<location path="central/sensor/service/pipeline/virtualmachineindex/pipeline.go" line_range="132-144" />
<code_context>
+				Reason:      reason,
+			},
+		},
+	}); err != nil {
+		log.Warnf("Failed injecting SensorACK (%s) for VM index report (vm_id=%s): %v", action, vmID, err)
+	}
+}
</code_context>
<issue_to_address>
**suggestion:** Use a more appropriate format verb for the SensorACK_Action enum in the warning log.

`action` is a `central.SensorACK_Action` enum. With `%s`, you’ll just get its numeric value rendered as a string, which isn’t useful and can be misleading in logs. Prefer `%v` (or `%d` for the numeric value), or keep `%s` only if you explicitly convert `action` to a string representation first.

```suggestion
	if err := injector.InjectMessage(ctx, &central.MsgToSensor{
		Msg: &central.MsgToSensor_SensorAck{
			SensorAck: &central.SensorACK{
				Action:      action,
				MessageType: central.SensorACK_VM_INDEX_REPORT,
				ResourceId:  vmID,
				Reason:      reason,
			},
		},
	}); err != nil {
		log.Warnf("Failed injecting SensorACK (%v) for VM index report (vm_id=%s): %v", action, vmID, err)
	}
}
```
</issue_to_address>

Please address the comments from this code review:

## Overall Comments
- There are many repeated `SendSensorACK` calls in `pipeline.Run` with similar parameters; consider introducing a small helper (e.g., `sendVMIndexACK/NACK`) to centralize messageType and reason handling and reduce duplication/error risk.
- In `sensorConnection.multiplexedPush`, when emitting a NACK for rate-limited VM index reports you always use `SensorACKReasonRateLimited`; if the rate limiter provides more specific context, consider including or mapping that information so sensor-side behavior can distinguish different rate-limit scenarios if needed.