partman: partial profile cleanups

Cleanup partman profiles a bit; this is mostly:
- Whitespace/comments
- Getting rid of redundant & ugly partman-auto/init_automatically_partition
- Using "finish" as the partman/choose_partition value, not the whole
  descriptive text.

Additionally, this renames the "LVS" profile to "flat" (and switches it
to ext4) as it is generally useful and used by non-LVS servers already.

Change-Id: Ibd3277fe352a22007a1a39da10dbaef3dfb9815c