**Describe the bug**

When we send a CONNECT packet (MQTT version 3.1) that carries the will topic to NanoMQ, NanoMQ saves such a will message; when a subsequent client initiates a normal subscription to the will topic, NanoMQ accidentally forwards the will message to the client, and it is still of the Reserved type, which violates two rules:

1. The broker can only send a will message on the corresponding topic if the subscribing client disconnects unexpectedly
2. Reserved messages are prohibited.

**To Reproduce**

First, send the Connect packet
```
echo 103d00064d51497364700376225e0003675977000146000c5141674e586e367750775051001949764873317a50305355644d6842777a7254486747644d4d4b | xxd -p -r | nc 172.17.0.6 1883
```
Then, send the Connect and Subscribe Packet
```
echo 107300064d514973647003d49498001432764656424f365950574739704650435463565a00076b724a5448616c000b787a5353526f444bff44430019664f4739766c306a77595165793057586346364576315a4a6e001e383952707861723265476d793635444d69745478764f754c6f58595a7a308217d08e000434586c79000001460000074b58597530484501 | xxd -p -r | nc 172.17.0.6 1883
```
![image](https://github.com/nanomq/nanomq/assets/44093631/3899da1f-8ae5-4425-8308-e2df00642b08)



**Environment Details**
 - NanoMQ 0.21.8

**Client SDK**
If possible include the mqtt sdk you used to connect to nanomq
Minimal C test cases are perferred.

**Additional context**
Add any other context about the problem here.

NanoMQ accidentally send Reserved-type packets to clients
This is a GitHub Issue
repo:nanomq
owner:emqx
Title : NanoMQ accidentally send Reserved-type packets to clients
Issue date:

--- start body ---
**Describe the bug**

When we send a CONNECT packet (MQTT version 3.1) that carries the will topic to NanoMQ, NanoMQ saves such a will message; when a subsequent client initiates a normal subscription to the will topic, NanoMQ accidentally forwards the will message to the client, and it is still of the Reserved type, which violates two rules:

1. The broker can only send a will message on the corresponding topic if the subscribing client disconnects unexpectedly
2. Reserved messages are prohibited.

**To Reproduce**

First, send the Connect packet
```
echo 103d00064d51497364700376225e0003675977000146000c5141674e586e367750775051001949764873317a50305355644d6842777a7254486747644d4d4b | xxd -p -r | nc 172.17.0.6 1883
```
Then, send the Connect and Subscribe Packet
```
echo 107300064d514973647003d49498001432764656424f365950574739704650435463565a00076b724a5448616c000b787a5353526f444bff44430019664f4739766c306a77595165793057586346364576315a4a6e001e383952707861723265476d793635444d69745478764f754c6f58595a7a308217d08e000434586c79000001460000074b58597530484501 | xxd -p -r | nc 172.17.0.6 1883
```
![image](https://github.com/nanomq/nanomq/assets/44093631/3899da1f-8ae5-4425-8308-e2df00642b08)



**Environment Details**
 - NanoMQ 0.21.8

**Client SDK**
If possible include the mqtt sdk you used to connect to nanomq
Minimal C test cases are perferred.

**Additional context**
Add any other context about the problem here.

--- end body ---
