release-process: create a stable branch when preparing a new release

[ptrus]

Currently we create a stable release branch only once we need to backport some
changes. This PR changes the release process to create the stable branch when
creating a new release. This will ensure CI jobs hooked to stable/ branches,
such as building a release tagged CI docker image will be run for every
release.

NOTE: this could probably be automated within the tag-next-release make step (with an additional check to only run this when creating a new release and not when backporting), but I'm afraid i'm not enough of a makefile enthusiast to tackle that :/ - can open an issue though.

[tjanez]

Currently we create a stable release branch only once we need to backport some
changes. This PR changes the release process to create the stable branch when
creating a new release. This will ensure CI jobs hooked to stable/ branches,
such as building a release tagged CI docker image will be run for every
release.

Just want to clarify, we still want to do YY.X releases on the master branch because it will give us a reasonable good overall Change log (with all previous YY.X-1, ... releases in there).

NOTE: this could probably be automated within the tag-next-release make step (with an additional check to only run this when creating a new release and not when backporting), but I'm afraid i'm not enough of a makefile enthusiast to tackle that :/ - can open an issue though.

😁 Fair enough. Please, file an issue so we don't forget about it.

[tjanez]

Suggested change

	release: create a stable branch when preparing a new release
	release: Create a stable branch when preparing a new release