Set Rich Text Editor (RTE) as default for new GitLab accounts

Description and Proposed Change

Currently, when users create a new GitLab account, the Plain Text Editor (PTE) is set as the default editor. This feature request proposes changing the system default to Rich Text Editor (RTE) for all new user accounts.

Rationale

• Rich Text Editor provides a more intuitive experience for new users
• RTE offers better visibility of formatting options without requiring knowledge of markdown
• Would eliminate the need for new users to manually change this setting and improve discoverability of the RTE

Business Impact

• Improved onboarding experience for new users
• Reduced friction in the initial user experience
• Alignment with modern editor expectations in similar platforms

Implementation Considerations

• This change would only affect new accounts; existing user preferences would remain unchanged
• Clear documentation should accompany this change
• We should track RTE usage before and after implementation

Notes

This request originated from a discussion in https://gitlab.com/gitlab-org/gitlab/-/issues/527160+, this thread in particular.