test_result: fix display of durations

 - str() because in ERP5JS the duration are directly serialized to json,
   which is not allowed.
 - int() to have a second level precision, which is more readable.
14 jobs for fix/testresult-erp5js-duration in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-TestRunner2

01:30:20

failed ERP5.UnitTest-TestRunner2

05:50:44

passed ERP5.CodingStyleTest-TestRunner2

01:39:01

passed ERP5.CodingStyleTest-TestRunner2

00:41:42

passed ERP5.CodingStyleTest-TestRunner2

01:42:08

failed ERP5.CodingStyleTest-TestRunner2

04:25:15

passed ERP5.CodingStyleTest-TestRunner2

01:42:51

canceled ERP5.CodingStyleTest-TestRunner2

failed ERP5.UnitTest-TestRunner2

03:46:02

canceled ERP5.UnitTest-TestRunner2

failed ERP5.UnitTest-TestRunner2

01:20:29

failed ERP5.UnitTest-TestRunner2

02:50:33

failed ERP5.UnitTest-TestRunner2

02:53:19

failed ERP5.UnitTest-TestRunner2

06:01:37