Read certificates from localdata and preserve them during upgrades

[github-actions]

This is an automatic cherry-pick of edbe3a3e15701406caa3ba269db332124516ccef

The original PR was #187 with message:

This means certificates will be preserved during upgrades.

Checklist before requesting a review

• I have performed a self-review of my own code
• I have verified that the code builds perfectly fine on my local system
• I have added tests that prove my fix is effective or that my feature works
• I have commented my code, particularly in hard-to-understand areas
• I have verified that my code follows the style already available in the repository
• I have made corresponding changes to the documentation