Remove Debian 8 Test Slave
Remove Debian 8 Test Slave

The Debian 8 kernel doesn't add significant additional test
coverage and is therefore its test slave is being removed.
The Debian 8 build slave however will remain to ensure we
don't accidentally break the build on Debian.

Signed-off-by: Brian Behlendorf <32d50ad1e384dcb9a5bf7e40fa470df5dabaf348@llnl.gov>

gmelikov/zfs-buildbot,gmelikov/zfs-buildbot,zfsonlinux/zfs-buildbot,zfsonlinux/zfs-buildbot