Routing improvements

To get GitLab routing in a better share there are several initiatives I am working on:

Scoped routing /-/

The reasoning explained in #214217 (closed).

To achieve that we need to move global and project routes under - scope:

• Move all existing group routes under /-/ scope.
• Move all existing project routes under /-/ scope #29572 (closed)
• Move all global routes under /-/ scope #210024 (closed)
• Ensure new routes are going under /-/ scope #29130 (closed)

Route regex

Reduce routing regex complexity and prevent introducing new reserved words

• Ensure we don't add new entries to TOP_LEVEL_ROUTES and PROJECT_WILDCARD_ROUTES. !30162 (merged)
• Reduce amount of items above to minimize regex complexity. #28803 (closed)
• Investigate regex use in project and group constraints

Routing cleanup

• Order routes alphabetically #210490 (closed)
• Remove deprecated routes #28848 (closed)
• Update robots.txt to keep up with routing changes => !34773 (merged)