Fix docker in docker not working in ubuntu 26.04

[SrzStephen]

Closes #1633

#1235 references fedora specifically and I see a few merges that are already in that seem to be fedora specific

I have intentionally tried to only touch the existing ubuntu components that I am able to test

Testing

devcontainer features test --features docker-in-docker --filter docker_build --project-folder .

Before

🔄 Testing 'docker-ps'

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?


❌ docker-ps check failed.

🔄 Testing 'docker-build'

ERROR: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?


❌ docker-build check failed.

After

Test Passed!
🧪 Executing duplicate test for feature 'docker-in-docker'...
⚠️ Skipping duplicate test for docker-in-docker because '/home/stephen/code/patch-features/test/docker-in-docker/duplicate.sh' does not exist.


  ================== TEST REPORT ==================
✅ Passed:      'docker-in-docker'
✅ Passed:      'docker_build_fallback_compose'
✅ Passed:      'docker_build'
✅ Passed:      'docker_build_with_compose_switch'
✅ Passed:      'docker_build_2'
✅ Passed:      'docker_build_older'
✅ Passed:      'docker_build_no_compose'
✅ Passed:      'docker_buildx'
✅ Passed:      'docker_build_fallback_buildx'

[SrzStephen]

I'm trying to touch the least code possible since I don't fully understand why the debian specific check was added here

#1425 looks like it's trying to accomplish a similar thing but lacks the fallback that this has so the tests fail, arguably this PR should be made on top of that since #1425 has actually added tests for this case, but I'm not sure why it hasn't been merged in yet so I'm trying a smaller commit here.

fork-features on  fix-1235 [!]
❯ devcontainer features test --features docker-in-docker --filter docker_build --project-folder .

🔄 Testing 'docker-ps'

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?


❌ docker-ps check failed.

Edit:
I've made some changes on top of #1425 https://github.com/SrzStephen/fork-features/tree/fix-1235 , I'll see how Oliver wants to deal with it.