Refactor CI/CD landing page

What does this MR do?

Ports changed related to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24894 to EE.

Related issues

Relates to: https://gitlab.com/gitlab-org/gitlab-ce/issues/56973 and https://gitlab.com/gitlab-org/gitlab-ce/issues/50498.

Author's checklist

• Apply the correct labels and milestone
• Correctly apply the product badges and tiers
• Port the MR to EE (or backport from CE): https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24894

Review checklist

• Your team's review (required)
• PM's review (recommended, but not a blocker)
• Technical writer's review (required)
• Merge the EE-MR first, CE-MR afterwards (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24894)