chore: Remove docker directory (backport #355)

[mergify]

We use the official Espressif docker image, and therefore, don't need this.
Instructions for docker are located here in the README.

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This is an automatic backport of pull request #355 done by Mergify.

[mergify]

Cherry-pick of fc2749c has failed:

On branch mergify/bp/jazzy/pr-355
Your branch is up to date with 'origin/jazzy'.

You are currently cherry-picking commit fc2749c.
  (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:
	deleted:    docker/Dockerfile

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by them: docker/install_micro_ros_deps_script.sh

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