Update PostgreSQL 12 from 12.3 to 12.4

What does this MR do?

Updates PostgreSQL 12 from 12.3 to 12.4.

12.4 release: https://www.postgresql.org/about/news/2060/

Checklist

See Definition of done.

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Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
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• Pipeline is green on dev.gitlab.org if the change is touching anything besides documentation or internal cookbooks
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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
• Integration tests added to GitLab QA
• Equivalent MR/issue for the GitLab Chart opened