Remove cylinder size adjustments in the copy dialog (#749867)

BUF in the copy dialog class, Dialog_Partition_Copy, is use to adjust
limits in 2 cases:

1) Minimum size when copying an XFS file system

Minimum size was set to the used space + 2 * cylinder size (typically
plus ~16 MiB).  This commit from 2004-12-20 added it:
    a54b52ea
    xfs copy now uses xfsdump and xfsrestore. icw some hacks in the other 2

Issues:
* This is increasing the minimum XFS file system size when copying it,
  which doesn't happen in the resize case for other file systems.
* It allows an XFS file system to be created which is smaller than the
  minimum size allowed by GParted.  Copying an empty XFS file system can
  create a new file system as small as 26 MiB.  This is smaller than the
  minimum GParted allows of 32 MiB because that is the minimum
  xfs_repair can handle.

Remove this addition when copying an XFS file system and enforce minimum
file system size.

2) Maximum size when copying a file system into empty space larger than
   it's maximum size

Maximum size was set to maximum file system size - cylinder size
(typically minus ~8 MiB).  Only applied to FAT16 which has a maximum
file system size set in and can be grown.  Added by this commit from
2004-12-15:
    10e8f333
    :get_fs now returns a const reference. in copy and resizedialog
    ...
    * in copy and resizedialog filesystems with MAX set now have a max size of MAX - one cylinder .

Issue:
* This is applying a lower maximum resize when copying the file system
  compared to that when creating the file system.
  NOTE:
  GParted currently allows all file systems to be resize to any size,
  regardless of the maximum file system size.  This is probably an
  oversight, but it does allow libparted to convert FAT16 to FAT32 file
  system when resizing.

Remove this lower maximum file system size when copying and resizing,
compared to creating.

Bug 749867 - Some limits are adjusted by arcane cylinder size amount
             when copying and resizing in a single operation