Update translated free trial pages with GitLab Duo Agent Platform changes

Summary

This MR updates the translated free trial pages to match the English changes from !3735 (merged).

Review app:

• https://feb10-free-trial.about.gitlab-review.app/de-de/free-trial/devsecops/ (change locale using language selector)
• https://feb10-free-trial.about.gitlab-review.app/de-de/free-trial/ (change locale using language selector)

Languages Updated

• 🇩🇪 German (de-de)
• 🇫🇷 French (fr-fr)
• 🇯🇵 Japanese (ja-jp)
• 🇧🇷 Portuguese (pt-br)
• 🇮🇹 Italian (it-it)
• 🇪🇸 Spanish (es)

Changes Made

free-trial/index.yml updates:

1. Header subtext: Added "and access to GitLab Duo Agent Platform" to the trial features description
2. Trial end messaging: Changed from "enjoy GitLab Free (forever!)" to "continue with free features or upgrade to a paid plan"
3. FAQ - What's included:
   • Updated to include GitLab Duo Agent Platform and 24 credits per user
   • Added service accounts exclusion
   • Added data-ga tracking attributes to links
4. FAQ - What happens after trial ends:
   • Updated to mention losing access to GitLab Duo Agent Platform
   • Updated to mention losing remaining credits from trial period

free-trial/devsecops/index.yml updates:

1. File structure: Moved devsecops.yml → devsecops/index.yml to match English file structure
2. Accordion items:
   • Replaced "Deliver secure software faster" with "Automate workflows with AI agents"
   • Replaced "AI across the SDLC" with "Protect the integrity of your software"
   • Removed the old "Built-in security and governance" accordion item (now only 3 items instead of 4)

Related MR

• !3735 (merged) (original English changes)