t: Stabilize ui/10-tests_overview.t

This fixes "Failed test 'description popover shows content' at
t/ui/10-tests_overview.t line 168." that we see often recently. Probably
reading the description is a tad slower but the test was not taking the
popup time into account anyway so this should be fixed.

t/ui/10-tests_overview.t

@@ -165,6 +165,7 @@ like($driver->find_elements('.failedmodule', 'css')->[1]->get_attribute('href'),
 my @descriptions = $driver->find_elements('td.name a', 'css');
 is(scalar @descriptions, 2, 'only test suites with description content are shown as links');
 $descriptions[0]->click();
+wait_for_ajax(msg => 'wait for popover on kde');
 is($driver->find_element('.popover-header')->get_text, 'kde', 'description popover shows content');
 
 # Test bug status
@@ -353,6 +354,7 @@ subtest "job template names displayed on 'Test result overview' page" => sub {
     my @descriptions = $driver->find_elements('td.name a', 'css');
     is(scalar @descriptions, 2, 'only test suites with description content are shown as links');
     $descriptions[0]->click();
+    wait_for_ajax(msg => 'wait for popover on kde_variant');
     is(wait_for_element(selector => '.popover-header')->get_text, 'kde_variant', 'description popover shows content');
 };