feat(legacy): trim overbooked shows after autoloading a playlist (#2897)

### Description

Some combination of preload/postload and autoloding playlists with
smartblocks generate massively overbooked shows that clutter up the
interface. This addition performs a 'trim overbooked' after filling up
the autoload list, and does the same as pushing the 'trim overbooked'
button in the UI.


### Testing Notes

Define an autoloading playlist of 2 hours and schedule it for a one hour
show. Without patch, you'll get entries for 2 hours, with the patch, you
only get one hour and a 'overboarding' orange entry at most.

---------

Co-authored-by: Kyle Robbertze <paddatrapper@users.noreply.github.com>
Co-authored-by: Thomas Göttgens <tgoettgens@mail.com>
Co-authored-by: jo <ljonas@riseup.net>

legacy/application/views/scripts/form/preferences_general.phtml

@@ -45,6 +45,9 @@
 
         <?php echo $this->element->getElement('thirdPartyApi')->render() ?>
 
+        <?php echo $this->element->getElement('scheduleTrimOverbooked')->renderViewHelper() ?>
+        <?php echo $this->element->getElement('scheduleTrimOverbooked')->renderLabel() ?>
+        <br/>
         <?php echo $this->element->getElement('radioPageLoginButton')->renderViewHelper() ?>
         <?php echo $this->element->getElement('radioPageLoginButton')->renderLabel() ?>
         <br />