Consolidate GADS pages from 6 to 3 persona-based pages

Based on feedback, consolidated from 6 category pages to 3 persona-based landing pages:

1. Platform Teams (/gads/platform-teams/) - merges platform engineering + developer platforms
   Keywords: platform engineering, internal developer platform, developer productivity platform

2. Infrastructure/DevOps Engineers (/gads/infrastructure-engineers/) - merges IaC + DevOps automation + cloud infrastructure automation
   Keywords: IaC tools, DevOps automation, cloud infrastructure automation

3. Multi-Cloud Operations (/gads/multicloud/) - kept separate
   Keywords: multi-cloud, cross-cloud, hybrid cloud

Each page uses appropriate UTM source tracking and category-specific DKI placeholders. All pages maintain style guide compliance (no 'easiest' or 'simple').

Author: asafashirov