Schedule frequent docker-publish but only act when there a new docker tag would be created

[dsavchenko]

• the tag includes sha of the last commit in this repo, use the one produced by make.sh compute-version to reflect changes in other components
• given previous point, we can schedule the action more often, but rely on the available image tags to check if there are changes and the build needs to be run

[volodymyrss]

For now it's meant to be updated like dispatcher container, by the bot controller behavior: reacting on updates in relevant repositories and committing here.

Scheduled updates are somehow more reliable, but they will introduce potentially quite a delay.
Maybe both ways can be used?