tradefed tests: add support for specifying number for failed test case to be printed

the lava side will report timeout problem if we print
too many failed test cases in the lava log.
here we add support to specify the number to print for each job,

Change-Id: Ia4937ac1bdba6eea65cb5162e8e62d6048eb3b94
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
3 files changed