minor symfony#9064 Fixed the default value for toolbar configuration (nicosomb)

This PR was submitted for the 4.0 branch but it was merged into the 2.7 branch instead (closes symfony#9064).

Discussion
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Fixed the default value for toolbar configuration

Because the below full default configuration shows that `toolbar` is set to `false`, we need to add consistence here.

Commits
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1b78c34 Fixed the default value for toolbar configuration

Author: javiereguiluz

reference/configuration/web_profiler.rst

@@ -23,7 +23,7 @@ Configuration
 toolbar
 ~~~~~~~
 
-**type**: ``boolean`` **default**: ``true``
+**type**: ``boolean`` **default**: ``false``
 
 It enables and disables the toolbar entirely. Usually you set this to ``true``
 in the ``dev`` and ``test`` environments and to ``false`` in the ``prod``