Remove code for updating gitconfig and change DefaultBundlePath value

What does this MR do?

This MR does the following:

• removes a change that was originally added in order to solve git certificate error with ADDITIONAL_CA_CERT_BUNDLE on alpine containers, however, there's a better approach as described here
• Updates the DefaultBundlePath from /etc/ssl/certs/ca-cert-additional-gitlab-bundle.pem to /etc/ssl/certs/ca-certificates.crt. This change will enable the certificate stored in ADDITIONAL_CA_CERT_BUNDLE to be used by tools such as git without any additional work.

What are the relevant issue numbers?

gitlab-org/gitlab#334999 (closed)

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
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer