design: simplify how luxid determins job termination
design: simplify how luxid determins job termination

With the job files, we already have designated files per job. So
there is no need to additionally signal through a socket regular
job termination. This design also has the advantage that it is
already implemented and working in current luxid.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

leshchevds/ganeti,leshchevds/ganeti,andir/ganeti,yiannist/ganeti,bitemyapp/ganeti,andir/ganeti,leshchevds/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,apyrgio/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,ganeti/ganeti,andir/ganeti,yiannist/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti,onponomarev/ganeti,onponomarev/ganeti,dimara/ganeti,apyrgio/ganeti,mbakke/ganeti,mbakke/ganeti