Remove requirement for Docker daemon experimental mode from image build scripts

What does this MR do?

Removes the setup required to use the experimental mode in the docker daemon, and related checks.

Why was this MR needed?

When testing with minikube for !2705 (merged), the helper image build script would not allow proceeding because the Docker daemon set up by minikube doesn't support experimental mode. After commenting out the check, I noticed that the build was successful and usable. After that, I saw that docker buildx is no longer listed as an experimental feature.

What's the best way to test this MR?

The helper image and development docker jobs should pass for all non-amd64 targets (e.g. arm, arm64, etc).

What are the relevant issue numbers?

Closes #27491 (closed)