minor #13986 Fix OPcache class preload requirement (ITernovtsiy)

This PR was merged into the 4.4 branch.

Discussion
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Fix OPcache class preload requirement

`container.dumper.inline_factories`
As stated by @nicolas-grekas in symfony/symfony#32581 (comment)
> With preloading, a single big file can, in theory, be similarly fast or faster.

`container.dumper.inline_class_loader`
With this parameter set to `true`, we'll do extra `include_once` for classes already preloaded by OPcache.
Additionally, it can lead to warnings (cannot redeclare class) in classes that use `class_alias`, like https://github.com/FriendsOfSymfony/FOSHttpCacheBundle/blob/master/src/EventListener/InvalidationListener.php#L33
It's because this class already declared in preload, and PHP tries to declare it again after `include_once` in service getter.

Commits
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cc151fc Remove incorrect opcache preload instructions

Author: OskarStark

performance.rst

@@ -109,9 +109,7 @@ During container compilation (e.g. when running the ``cache:clear`` command),
 Symfony generates a file called ``preload.php`` in the ``config/`` directory
 with the list of classes to preload.
 
-The only requirement is that you need to set both ``container.dumper.inline_factories``
-and ``container.dumper.inline_class_loader`` parameters to ``true``. Then, you
-can configure PHP to use this preload file:
+You can configure PHP to use this preload file:
 
 .. code-block:: ini