resize/test-virt-resize.pl: Make partitions larger in the test

Sometimes the test would fail with the error below.  By making the
partitions and the shrink size larger we should be able to avoid this.

$ ./test-virt-resize.pl --seed=16193061
seed:           16193061
partition type: gpt
nr partitions:  1
expand:         0
no extra part:  0
source format:  raw
target format:  qcow2
filesystem:     lvm
LV expand:
partition 1:    sda1 lvm shrink
lvcreate:   Volume group "VG" has insufficient free space (63 extents): 64 required. at ./test-virt-resize.pl line 282.

Author: rwmjones

resize/test-virt-resize.pl

@@ -64,11 +64,11 @@
 $| = 1;
 
 # The size of each partition, in MB and sectors.
-my $part_size_mb = 512;
+my $part_size_mb = 1024;
 my $part_size_sectors = 1024 * 1024 * $part_size_mb / 512;
 
-my $expand_target_size_mb = 800;
-my $shrink_target_size_mb = 260;
+my $expand_target_size_mb = 1200;
+my $shrink_target_size_mb = 400;
 
 # Create the handle.
 my $g = Sys::Guestfs->new ();