fix: remove deprecated execute method for cronjob calls

Signed-off-by: Anna Larch <anna@nextcloud.com>

Author: miaulalala

tests/BackgroundJob/ExpireActivitiesTest.php

@@ -49,7 +49,7 @@ public function testExecute(): void {
 		$jobList = $this->createMock(IJobList::class);
 
 		/** @var JobList $jobList */
-		$backgroundJob->execute($jobList);
+		$backgroundJob->start($jobList);
 		$this->assertTrue(true);
 
 		// NOTE: the result of execute() is further tested in

tests/DataDeleteActivitiesTest.php

@@ -118,7 +118,7 @@ public function testExpireActivities(): void {
 		$backgroundjob->setId(1);
 		$this->assertUserActivities(['delete', 'otherUser']);
 		$jobList = $this->createMock(IJobList::class);
-		$backgroundjob->execute($jobList);
+		$backgroundjob->start($jobList);
 		$this->assertUserActivities(['otherUser']);
 	}