Fix GitLab base caching (Backport 18.9)

What does this MR do and why?

Backport !2845 (merged) to 18.9 to avoid pulling the wrong gomplate version into any release as seen in gitlab-org/charts/gitlab#6297 (closed).

Relates Workhorse template uses deprecated `slice` func... (gitlab-org/charts/gitlab#6297 - closed)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).

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