Retry helper image build

What does this MR do?

Retry helper image build

Why was this MR needed?

We have seen in the past the buildx is sometimes unstable and fails to build an image because of network connectivity issues or some flaky resource. In !2087 (merged) we added retries for Docker builds.

In !2206 (merged) we introduced buildx to build the helper images as well, so we should add retries so we don't see failures like https://gitlab.com/gitlab-org/gitlab-runner/-/jobs/627685428

What are the relevant issue numbers?

closes #26550 (closed)