Backport of docker: Fix a bug where images with port number and no tags weren't parsed correctly into release/1.9.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #24547 to be assessed for backporting due to the inclusion of the label backport/1.9.x.

The below text is copied from the body of the original PR.

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Description

when using private registry without any image tag pull get Invalid reference format issue

Testing & Reproduction steps

on version 1.9.4 send a job with image with following format:

ghcr.service.consul:5000/paperless-ngx/paperless-ng

Reviewer Checklist

• Backport Labels Please add the correct backport labels as described by the internal
  backporting document.
• Commit Type Ensure the correct merge method is selected which should be "squash and merge"
  in the majority of situations. The main exceptions are long-lived feature branches or merges where
  history should be preserved.
• Enterprise PRs If this is an enterprise only PR, please add any required changelog entry
  within the public repository.

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Overview of commits

• 6469b59