Hide xfail/xleak test summary

We don't show succeeding tests in the summary, and for all intents and purposes,
these tests have succeeded, in that they behave as expected. I've seen the
output confuse people on multiple occasions, for example GH-17105.

Closes GH-17109

run-tests.php

@@ -3144,18 +3144,6 @@ function get_summary(bool $show_ext_summary): string
         $failed_test_summary .= "=====================================================================\n";
     }
 
-    if (count($PHP_FAILED_TESTS['XFAILED'])) {
-        $failed_test_summary .= '
-=====================================================================
-EXPECTED FAILED TEST SUMMARY
----------------------------------------------------------------------
-';
-        foreach ($PHP_FAILED_TESTS['XFAILED'] as $failed_test_data) {
-            $failed_test_summary .= $failed_test_data['test_name'] . $failed_test_data['info'] . "\n";
-        }
-        $failed_test_summary .= "=====================================================================\n";
-    }
-
     if (count($PHP_FAILED_TESTS['BORKED'])) {
         $failed_test_summary .= '
 =====================================================================
@@ -3206,19 +3194,6 @@ function get_summary(bool $show_ext_summary): string
         $failed_test_summary .= "=====================================================================\n";
     }
 
-    if (count($PHP_FAILED_TESTS['XLEAKED'])) {
-        $failed_test_summary .= '
-=====================================================================
-EXPECTED LEAK TEST SUMMARY
----------------------------------------------------------------------
-';
-        foreach ($PHP_FAILED_TESTS['XLEAKED'] as $failed_test_data) {
-            $failed_test_summary .= $failed_test_data['test_name'] . $failed_test_data['info'] . "\n";
-        }
-
-        $failed_test_summary .= "=====================================================================\n";
-    }
-
     if ($failed_test_summary && !getenv('NO_PHPTEST_SUMMARY')) {
         $summary .= $failed_test_summary;
     }