[Spike] Segregate buildx build of rails-ee and rails-ce

as can be seen in [CI] master pipeline failed, phase-five gitlab-... (#2265) currently buildx can start builds of gitlab-rails-ce and gitlab-rails-ee on the same node at the same time, which results in slowdowns and eventual failures. We need to look into possibilities of cordoning two builds

Deliverables

• Plan to segregate rails-ee and rails-ce builds
• Created issue to implement segregation