chore: Test trailing slash removal (will be closed as all work is on saas)

[istarkov]

Description

Do redirect on trailing slash

https://github.com/webstudio-is/webstudio-saas/pull/331

closes #4327

Steps for reproduction

Test following urls

https://slash-ubje8.wstd.work/test//// <-- Redirect
https://slash-ubje8.wstd.work/test/  <-- Redirect
https://slash-ubje8.wstd.work///  <-- Redirect
https://slash-ubje8.wstd.work  <-- Do nothing
https://slash-ubje8.wstd.work/  <-- Do nothing

Code Review

• hi @kof, I need you to do
  • conceptual review (architecture, feature-correctness)
  • detailed review (read every line)
  • test it on preview

Before requesting a review

• made a self-review
• added inline comments where things may be not obvious (the "why", not "what")

Before merging

• tested locally and on preview environment (preview dev login: 5de6)
• updated test cases document
• added tests
• if any new env variables are added, added them to .env file