centos7_docker_image_updater is still unreliable

A fix has been applied for the access to dockerhub in the PR below:

> @steelhead31 has updated our docker connetion to authenticate with a personal access token (PAT) instead of the previous credentials and this is allowing it to push the images up to dockerhub again.

_Originally posted by @sxa in [#2626](https://github.com/adoptium/infrastructure/issues/2626#issuecomment-3189177516)_

However the runs are still proving to be unreliable. We should go through the recent errors and try to see which can have fixes applied in order to try and make this process more reliable:

Start by reviewing the recent errors from centos7_docker_image_updater and the DockerHub authentication context described in the issue. Identify which failures can be fixed; done means actionable reliability fixes have been applied and the updater runs more consistently.

Written by the indexing model from the issue text.