Routes should be just imported, not mounted

[OndraM]

Routes should be just imported, they don't need to be mounted.

Before (note doubled route prefixes):

(master) $ bin/console debug:router
 -------------------------- -------- -------- ------ --------------------------------------------- 
  Name                       Method   Scheme   Host   Path                                         
 -------------------------- -------- -------- ------ --------------------------------------------- 
  _wdt                       ANY      ANY      ANY    /_wdt/_wdt/{token}                           
  _profiler_home             ANY      ANY      ANY    /_profiler/_profiler/                        
  _profiler_search           ANY      ANY      ANY    /_profiler/_profiler/search                  
  _profiler_search_bar       ANY      ANY      ANY    /_profiler/_profiler/search_bar              
...                  
 -------------------------- -------- -------- ------ --------------------------------------------- 

After:

(import-routes) $ bin/console debug:router
 -------------------------- -------- -------- ------ ----------------------------------- 
  Name                       Method   Scheme   Host   Path                               
 -------------------------- -------- -------- ------ ----------------------------------- 
  _wdt                       ANY      ANY      ANY    /_wdt/{token}                      
  _profiler_home             ANY      ANY      ANY    /_profiler/                        
  _profiler_search           ANY      ANY      ANY    /_profiler/search                  
  _profiler_search_bar       ANY      ANY      ANY    /_profiler/search_bar              
...                       
 -------------------------- -------- -------- ------ -----------------------------------

The problem originated from the cookbook I guess: symfony/symfony-docs#6612

[ikoene]

I had no idea this behavior occurred. Good job 👍