[submodule] Update submodule linkmgrd to the latest HEAD automatically (

#18016)

#### Why I did it
src/linkmgrd
```
* 70b6d15 - (HEAD -> 202311, origin/202311) [active-standby] Fix `show mux status` inconsistency introduced by orchagent rollback  (#225) (3 days ago) [Jing Zhang]
```
#### How I did it
#### How to verify it
#### Description for the changelog