Fix deprecated usage (#5050)

When using the command alias `sfcontainer` or `sfrouter`, the following warning occurs:

> ! [CAUTION] The use of "container:debug" command is deprecated since version 2.7 and will be removed in 3.0. Use the
> ! "debug:container" instead.

plugins/symfony2/symfony2.plugin.zsh

@@ -22,8 +22,8 @@ alias sf='`_symfony_console`'
 alias sfcl='sf cache:clear'
 alias sfsr='sf server:run -vvv'
 alias sfcw='sf cache:warmup'
-alias sfroute='sf router:debug'
+alias sfroute='sf debug:router'
-alias sfcontainer='sf container:debug'
+alias sfcontainer='sf debug:container'
 alias sfgb='sf generate:bundle'
 alias sfdev='sf --env=dev'
 alias sfprod='sf --env=prod'