Oniro Migration : reduce permission Maintainer to Developer

As part of the migration pipeline for Oniro, EF secrets has to be set via the gitlab UI -> Settings -> CI/CD -> Variables

Maintainer of the Oniro project can access to these secrets.

Actions:

• Reduce permission for Maintainer: @idlethread, @agherzan, @pastanki
• New request for project configuration in gitlab should be done in Helpdesk issues

/cc @fgurr @toscalix @mbarbero