unit tests: fix scalaris_cth exception if a testcase failed in init_per_testcase
unit tests: fix scalaris_cth exception if a testcase failed in init_per_testcase

-> also improved test duration reporting in general
scalaris-team/scalaris,jvf/scalaris,jvf/scalaris,caijieming-baidu/scalaris,scalaris-team/scalaris,jvf/scalaris,jvf/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,jvf/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,jvf/scalaris,scalaris-team/scalaris,caijieming-baidu/scalaris,scalaris-team/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,scalaris-team/scalaris,scalaris-team/scalaris