[BUGFIX] Documentation: use FQCN in Table Garbage Collection Tasks

The fully qualified class name of class `TableGarbageCollectionTask`
must be used to configure database tables, which should be cleaned up
(inactive or deleted records removed from the system).

This change replaces `tx_scheduler_TableGarbageCollection` with the
correct class name in the documentation:
\TYPO3\CMS\Scheduler\Task\TableGarbageCollectionTask::class

Releases: master
Resolves: #85205
Change-Id: I13434bf6bc13dd987263605d845f8b59b69e0796
Reviewed-on: https://review.typo3.org/57166


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>

typo3/sysext/scheduler/Documentation/Installation/BaseTasks/Index.rst

@@ -46,7 +46,7 @@ delete from the task configuration screen.
 It's also possible to clean up all configured table by
 checking the "Clean all available tables" box. The configuration for
 the tables to clean up is stored in
-:php:`$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['scheduler']['tasks']['tx_scheduler_TableGarbageCollection']['options']['tables']`.
+:php:`$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['scheduler']['tasks'][\TYPO3\CMS\Scheduler\Task\TableGarbageCollectionTask::class]['options']['tables']`.
 The syntax is the following:
 
 - option :php:`expireField` can be used to point to a table field
@@ -67,7 +67,7 @@ Example
 
 ::
 
-   $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['scheduler']['tasks']['tx_scheduler_TableGarbageCollection']['options']['tables'] = array(
+   $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['scheduler']['tasks'][\TYPO3\CMS\Scheduler\Task\TableGarbageCollectionTask::class]['options']['tables'] = array(
            'tx_realurl_errorlog' => array(
                    'dateField' => 'tstamp',
                    'expirePeriod' => '180'