bisect.jpl: catch exceptions outside of buildKernel()
bisect.jpl: catch exceptions outside of buildKernel()

To improve error handling logic, do not return a status from
buildKernel() but let it throw an exception if it fails and catch it
to set the status in the stage function.

Signed-off-by: Guillaume Tucker <e7e20b7c30f19d4ca6b81319ef81bf200369d137@collabora.com>

kernelci/lava-ci-staging,kernelci/lava-ci-staging,kernelci/lava-ci-staging