[docker_image_ctl.j2] skip hostname update if is up to date

[stepanblyschak]

Signed-off-by: Stepan Blyschak stepanb@mellanox.com

- What I did
Skip container hostname update in case container hostname is up to date.
This improves LAG restoration time during warm reboot by 10 seconds.

- How I did it
Implement a condition

- How to verify it

admin@r-boxer-sw01:~$ docker exec -it lldp hostname
r-boxer-sw01
admin@r-boxer-sw01:~$ redis-cli -n 4 hset 'DEVICE_METADATA|localhost' hostname sonic
admin@r-boxer-sw01:~$ sudo lldp.sh stop
admin@r-boxer-sw01:~$ sudo lldp.sh start
admin@r-boxer-sw01:~$ docker exec -it lldp hostname
sonic

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)

[jleveque]

Retest vsimage please

[jleveque]

Retest vsimage please

[stepanblyschak]

Retest vsimage please

[jleveque]

Retest vsimage please

[jleveque]

Retest vsimage please