Drop test cases that are exact duplicates

There are 100% identical duplicates in these files. I don't know
why. In some cases it was probably just a mistake. In other cases
it looks like the code was refactored and some parameter got lost,
which made some previously different test cases identical. Please
decide if this is critical and worth a closer look, or just merge
it as it was effectively dead code.

Change-Id: I13ee10cf1508dd65dde6bad6592bc0a94f8dcfd6

Author: thiemowmde

tests/unit/Entity/ItemTest.php

@@ -198,11 +198,6 @@ public function testItemWithSitelinksHasSitelinks() {
 		$this->assertFalse( $item->getSiteLinkList()->isEmpty() );
 	}
 
-	public function testItemWithoutSitelinksHasNoSitelinks() {
-		$item = new Item();
-		$this->assertTrue( $item->getSiteLinkList()->isEmpty() );
-	}
-
 	private function newStatement() {
 		$statement = new Statement( new PropertyNoValueSnak( 42 ) );
 		$statement->setGuid( 'kittens' );