CI: pin docker container tag to version

What does this MR do?

CI: pin docker container tag to version

• Add DOCKER_VERSION variable as 24.0.6
• Change all :dind to :${DOCKER_VERSION}-dind

Per CI documentation:

You should always pin a specific version of the image, like docker:24.0.5. If you use a tag like docker:latest, you have no control over which version is used. This can cause incompatibility problems when new versions are released.

Related issues

Closes #5184 (closed)

Author checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
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Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added/updated
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Equivalent MR/issue for Gitlab Operator project opened (see Operator documentation on impact of Charts changes)
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.