When a job is timed out during a test execution, we fail the test
and put status ERROR in the test. The job then exits with the rc
AVOCADO_TESTS_FAIL. This patch fixes this, making the test status
INTERRUPTED and the job to exit with AVOCADO_JOB_INTERRUPTED.

Also, when a job is timed out before a test, the test is skipped
and the job exits with rc AVOCADO_ALL_OK. For that case, this patch
makes the job to exit with AVOCADO_JOB_INTERRUPTED instead, keeping
the test status as SKIP.

Given this change, now we have the following combinations of test status
and job return code:

Case1:
    - Test1: PASS
    - Test2: SKIP (TestTimeoutSkip)

    Job RC: AVOCADO_JOB_INTERRUPTED

Case2:
    - Test1: PASS
    - Test2: INTERRUPTED (TestTimeoutInterrupted)
    - Test3: SKIP (TestTimeoutSkip)

    Job RC: AVOCADO_JOB_INTERRUPTED

Case3:
    - Test1: PASS
    - Test2: FAIL
    - Test3: INTERRUPTED (TestTimeoutInterrupted)
    - Test4: SKIP (TestTimeoutSkip)

    Job RC: AVOCADO_JOB_INTERRUPTED
Signed-off-by: NAmador Pahim <apahim@redhat.com>