Reports (classic or Data Visualization) don't natively support "latest row per group" logic you'd need to shape the data first. The cleanest approach:

1. Add a boolean field to sys_atf_test_suite_result, e.g. u_is_latest.

2. Create a Business Rule (after insert) on that table:
(function executeRule(current, previous) {
var prev = new GlideRecord('sys_atf_test_suite_result');
prev.addQuery('test_suite', current.test_suite);
prev.addQuery('sys_id', '!=', current.sys_id);
prev.addQuery('u_is_latest', true);
prev.query();
while (prev.next()) {
prev.u_is_latest = false;
prev.update();
}
current.u_is_latest = true;
})(current, previous);

3.Build your report/filter with a condition of u_is_latest = true now it always shows just the most recent run per suite.