[TASK] Add verbose output to report mail for failed tests

Adds the failed tests messages to the mail.

Change-Id: I104b7ad98b2ce1ab8014a0751f7adc8c72ad6ca2
Resolves: #58786
Related: #62101
Releases: master, 6.2
Reviewed-on: http://review.typo3.org/33749
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>