Fix media changelog test that did not expect delayed changelog entry

What happened was that in the place of the new `waitForTick`-call an
actual delay happened and therefore the file modification time and the
deletion entry were two different points in time, resulting in random
test failures. The test enforces this now, the condition to test has
been adjusted.

_test/tests/inc/changelog_getlastrevisionat.test.php

@@ -150,11 +150,16 @@ function test_deletedimage() {
         $revexpected = @filemtime(mediaFn($image));
         $rev = $revexpected + 10;
 
+        $this->waitForTick(true);
+
         $ret = media_delete($image, 0);
 
         $medialog = new MediaChangelog($image);
         $current = $medialog->getLastRevisionAt($rev);
-        $this->assertEquals($revexpected, $current);
+        // as we wait for a tick, we should get something greater than the timestamp
+        $this->assertGreaterThan($revexpected, $current);
+        // however, it should be less than the current time or equal to it
+        $this->assertLessThanOrEqual(time(), $current);
 
         //restore settings
         $_SERVER['REMOTE_USER'] = $oldRemoteUser;