[submodule] Update submodule sonic-mgmt-common to the latest HEAD automatically (sonic-net#17313)

#### Why I did it
src/sonic-mgmt-common
```
* 268b67c - (HEAD -> master, origin/master, origin/HEAD) Integrating the transformer infra GET optimization, Request context cancel handling and other bug fixes (#111) (2 hours ago) [Balachandar Mani]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld