Updating labels for on-demand runners

[MyroTk]

On-demand heztner server setup using https://github.com/testflows/TestFlows-GitHub-Runners

Labels of the jobs now include on-demand, which will trigger for on-demand runners to be brought up.
Further labels define Hetzner server types the runner will use (e.g. type-cpx31) and server image (image-x86-app-docker-ce).

[altinity-robot]

This is an automated comment for commit 6a7e191 with description of existing statuses. It's updated for the latest CI running
The full report is available here
The overall status of the commit is 🔴 failure

Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	🟡 pending
ClickHouse build check	Builds ClickHouse in various configurations for use in further steps. You have to fix the builds that fail. Build logs often has enough information to fix the error, but you might have to reproduce the failure locally. The cmake options can be found in the build log, grepping for cmake. Use these options and follow the general build process	🟢 success
Compatibility check	Checks that clickhouse binary runs on distributions with old libc versions. If it fails, ask a maintainer for help	🔴 failure
Docker image for servers	The check to build and optionally push the mentioned image to docker hub	🟢 success
Install packages	Checks that the built packages are installable in a clear environment	🟢 success
Integration tests	The integration tests report. In parenthesis the package type is given, and in square brackets are the optional part/total tests	🔴 failure
Mergeable Check	Checks if all other necessary checks are successful	🟢 success
Push to Dockerhub	The check for building and pushing the CI related docker images to docker hub	🟢 success
Ready for release	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	🟢 success
Stateful tests	Runs stateful functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	🟢 success
Stateless tests	Runs stateless functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	🟢 success

[Enmk]

Maybe just fork the ClickHouse/checkout and add retries there? Then we can reduce clutter here (to simplify merge) and even have a chance to propose these changes upstream.

[Enmk]

LGTM, please remove action.yml and retry.sh if those are not required.

[Enmk]

LGTM