Create standard-sized GPT linux disk image

[oldgalileo]

The current disk image included in the test fixtures has a size (in blocks) of 29. This was due to an error where the block bounds of the partition were not treated as inclusive. With this error in mind, the image was created with a first LBA of 34 and a last LBA of 64 (inclusive), for a total length of 29.

This should likely be updated to have a first LBA of 34 and a final LBA of 29, or for even more rigorous adherence to best practices a first LBA of 2048 for 1MiB alignment (at the very least, it should be 4k aligned).