Resolve "Move EE-specific stylesheets to `ee/app/assets/stylesheets` directory"

What does this MR do?

› git diff ce/master..origin/master --name-status ./app/assets/stylesheets | grep -e '^A' | cut -f2 | xargs -t -L1 -I % dirname % | xargs -t -L1 -I % mkdir -p ee/% 

dirname app/assets/stylesheets/framework/sortable.scss
mkdir -p ee/app/assets/stylesheets/framework
dirname app/assets/stylesheets/pages/billings.scss
dirname app/assets/stylesheets/pages/ee_start_trial.scss
mkdir -p ee/app/assets/stylesheets/pages
mkdir -p ee/app/assets/stylesheets/pages
dirname app/assets/stylesheets/pages/geo_nodes.scss
dirname app/assets/stylesheets/pages/issues/related_issues.scss
mkdir -p ee/app/assets/stylesheets/pages
mkdir -p ee/app/assets/stylesheets/pages/issues
dirname app/assets/stylesheets/pages/licenses.scss
dirname app/assets/stylesheets/pages/promotions.scss
mkdir -p ee/app/assets/stylesheets/pages
mkdir -p ee/app/assets/stylesheets/pages

and then

› git diff ce/master..origin/master --name-status ./app/assets/stylesheets | grep -e '^A' | cut -f2 | xargs -t -L1 -I % git mv % ee/%

git mv app/assets/stylesheets/framework/sortable.scss ee/app/assets/stylesheets/framework/sortable.scss
git mv app/assets/stylesheets/pages/billings.scss ee/app/assets/stylesheets/pages/billings.scss
git mv app/assets/stylesheets/pages/ee_start_trial.scss ee/app/assets/stylesheets/pages/ee_start_trial.scss
git mv app/assets/stylesheets/pages/geo_nodes.scss ee/app/assets/stylesheets/pages/geo_nodes.scss
git mv app/assets/stylesheets/pages/issues/related_issues.scss ee/app/assets/stylesheets/pages/issues/related_issues.scss
git mv app/assets/stylesheets/pages/licenses.scss ee/app/assets/stylesheets/pages/licenses.scss
git mv app/assets/stylesheets/pages/promotions.scss ee/app/assets/stylesheets/pages/promotions.scss

Does this MR meet the acceptance criteria?

• Review
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan

What are the relevant issue numbers?

Closes #4631 (closed)