Use the TestCase job error message as failure comment
Use the TestCase job error message as failure comment

If no failure comment exists, the UI already shows the testcase
error message for the job test case as a failure comment. Carry
this behaviour through to the Scheduler Reports Failed Jobs Table.

Change-Id: Iee23945efd6f3eca41adb8f49ded4eaa8b9210e3

Linaro/lava-server,Linaro/lava-server,Linaro/lava-server,Linaro/lava-server