tools: fix TypeError from test.py --time

Calculated durations are timedelta objects but the FormatTime function
is expecting a number in seconds.

PR-URL: #20368
Fixes: #20341
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

tools/test.py

@@ -1747,7 +1747,7 @@ def DoSkip(case):
     timed_tests.sort(lambda a, b: a.CompareTime(b))
     index = 1
     for entry in timed_tests[:20]:
-      t = FormatTime(entry.duration)
+      t = FormatTime(entry.duration.total_seconds())
       sys.stderr.write("%4i (%s) %s\n" % (index, t, entry.GetLabel()))
       index += 1