Remove dependency to docker.io (backport #985)

[mergify]

The dependency was basically added since this is needed to spawn up ursim. However, the start_ursim script catches the case that no docker executable is available and the tests requiring it are behind a compile definition which is off by default.

So, in order to not install docker for users automatically, the dependency shall be removed.

As a side-effect this has always stopped us from releasing the package for RHEL.

This closes #769

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This is an automatic backport of pull request #985 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 585e29f has failed:

On branch mergify/bp/humble/pr-985
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit 585e29f.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   ur_robot_driver/package.xml

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   .github/workflows/reusable_ici.yml

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[fmauch]

Looks good although I ask myself, why we don't use the reusable ici on the humble branch.