Labs: Make images create LVM at firstboot.sh

Possibly rebooting to do so; this allows maximum flexibility
since vmbuilder is unable to speak LVM, and fixed-size paritions
are intrinsically evil.

The VG this create is (purposefully) named the same as that which
is created by the labs_lvm module so that they are mutually
compatible.

Change-Id: I2e50e219ef955a927128b72cd55260caeedf6f50
Bug: 71873
Merge "Labs: Make images create LVM at firstboot.sh" into production