Append newline when writing CA certificate

What does this MR do?

This MR fixes a bug which resulted in the CA Certificate file being invalid if the analyzer is run multiple times. The fix adds newlines when writing the CA Certificate file, ensuring that the resulting file is valid, even when a CA Certificate is appended multiple times.

What are the relevant issue numbers?

gitlab-org/gitlab#236199 (closed)

Testing

Tested here

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
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• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer