Reset the peak memory usage for each job in BackgroundQueuePerformAction

This is specifically implemented in the controller instead of the
BackgroundQueueHandler, since the controller only has a single purpose:
Executing multiple different and a-priori unknown jobs. Measuring the peak
memory usage of the entire request is not useful there.

For other, user-facing, controllers the peak memory usage of an entire request
is more meaningful, since they also perform other tasks besides executing
background jobs. Thus we do not perform the reset in a generic location.

Author: TimWolla

wcfsetup/install/files/lib/action/BackgroundQueuePerformAction.class.php

@@ -29,6 +29,13 @@ public function execute()
         parent::execute();
 
         for ($i = 0; $i < self::$jobsPerRun; $i++) {
+            // Reset the memory usage for each background job, allowing to measure each individual
+            // background job's memory usage without a memory-heavy job skewing the numbers for
+            // the following jobs.
+            if (\PHP_VERSION_ID >= 80200) {
+                \memory_reset_peak_usage();
+            }
+
             if (BackgroundQueueHandler::getInstance()->performNextJob() === false) {
                 // there were no more jobs
                 break;