minor #19791 [Scheduler] Remove incorrect mention of subtracting time from jitter (Te4g)

This PR was submitted for the 6.3 branch but it was merged into the 6.4 branch instead.

Discussion
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[Scheduler] Remove incorrect mention of subtracting time from jitter

As we can see in the [code](https://github.com/symfony/symfony/blob/6.3/src/Symfony/Component/Scheduler/Trigger/JitterTrigger.php)  we can only add time.

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Commits
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ca5065a [Scheduler] Remove incorrect mention of subtracting time from jitter

Author: javiereguiluz

scheduler.rst

@@ -153,7 +153,7 @@ the frequency of the message. Symfony provides different types of triggers:
 
 :class:`Symfony\\Component\\Scheduler\\Trigger\\JitterTrigger`
     A trigger that adds a random jitter to a given trigger. The jitter is some
-    time that it's added/subtracted to the original triggering date/time. This
+    time that is added to the original triggering date/time. This
     allows to distribute the load of the scheduled tasks instead of running them
     all at the exact same time.