[Yardstick] add apt-get autoremove to free up disk space

[Yardstick] add apt-get autoremove to free up disk space

yardstick builds are failing due to running out of disk space
when too many kernels are left installed.

Try apt-get autoremove to cleanup before updating

[yardstick-verify-master] $ /bin/bash /tmp/jenkins4572301318127685434.sh
Reading package lists...
Building dependency tree...
Reading state information...
build-essential is already the newest version (12.1ubuntu2).
python3-dev is already the newest version (3.5.1-3).
python-dev is already the newest version (2.7.12-1~16.04).
The following packages were automatically installed and are no longer required:
  linux-headers-4.4.0-101 linux-headers-4.4.0-101-generic
  linux-headers-4.4.0-103 linux-headers-4.4.0-103-generic
  linux-headers-4.4.0-104 linux-headers-4.4.0-104-generic
  linux-headers-4.4.0-108 linux-headers-4.4.0-108-generic
  linux-headers-4.4.0-109 linux-headers-4.4.0-109-generic
  linux-image-4.4.0-101-generic linux-image-4.4.0-103-generic
  linux-image-4.4.0-104-generic linux-image-4.4.0-108-generic
  linux-image-4.4.0-109-generic linux-image-extra-4.4.0-101-generic
  linux-image-extra-4.4.0-103-generic linux-image-extra-4.4.0-104-generic
  linux-image-extra-4.4.0-108-generic linux-image-extra-4.4.0-109-generic
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 111 not upgraded.
4 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up linux-image-extra-4.4.0-116-generic (4.4.0-116.140) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-116-generic /boot/vmlinuz-4.4.0-116-generic
run-parts: executing /etc/kernel/postinst.d/dkms 4.4.0-116-generic /boot/vmlinuz-4.4.0-116-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-116-generic /boot/vmlinuz-4.4.0-116-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-116-generic
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.

gzip: stdout: No space left on device
E: mkinitramfs failure cpio 141 gzip 1
update-initramfs: failed for /boot/initrd.img-4.4.0-116-generic with 1.

Change-Id: I79396162c5300c8cbaecc474473af81842f79db8
Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>