fix: dind hostname and image details

[roleyfoley]

Description

Minor fixes to the dind extension following testing

• Ensures the hostname doesn't contain _ characters which aren't supported
• Sets that attributes for the dind images

Motivation and Context

The image configuration in solution was removes and replaced with image sourcing the hostname is from the migration to extensions

How Has This Been Tested?

Tested locally

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves the structure or operation of the implementation)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Followup Actions

• None

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• None of the above.