minor #17576 [DependencyInjection] Remove not implemented behavior (upyx)

This PR was squashed before being merged into the 5.4 branch.

Discussion
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[DependencyInjection] Remove not implemented behavior

Currently numeric keys are used, but it will be deprecated and changed in 7.0.

Deprecation: symfony/symfony#48686
New behavior: symfony/symfony#48653

Commits
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a8770de [DependencyInjection] Remove not implemented behavior

Author: javiereguiluz

service_container/service_subscribers_locators.rst

@@ -309,8 +309,6 @@ or directly via PHP attributes:
                     <argument type="service_locator">
                         <argument key="App\FooCommand" type="service" id="app.command_handler.foo"/>
                         <argument key="App\BarCommand" type="service" id="app.command_handler.bar"/>
-                        <!-- if the element has no key, the ID of the original service is used -->
-                        <argument type="service" id="app.command_handler.baz"/>
                     </argument>
                 </service>
             </services>
@@ -331,8 +329,6 @@ or directly via PHP attributes:
                     // In versions earlier to Symfony 5.1 the service() function was called ref()
                     'App\FooCommand' => service('app.command_handler.foo'),
                     'App\BarCommand' => service('app.command_handler.bar'),
-                    // if the element has no key, the ID of the original service is used
-                    service('app.command_handler.baz'),
                 ])]);
         };