tests/bluestore_types: Fixed data generation bluestore_blob_t::release_extents

tests/bluestore_types: Fixed data generation bluestore_blob_t::release_extents

The #1 and #2 elements could form a continuous sequence but still not
joined:
Expected equality of these values:
  result
    Which is: { 0x7b138000~48000, 0x883b0000~48000, 0xf0c10000~10000, 0x727b8000~38000 }
  mid
    Which is: { 0x7b138000~30000, 0x7b168000~18000, 0x883b0000~48000, 0xf0c10000~10000, 0x727b8000~38000 }

Signed-off-by: Adam Kupczyk <akupczyk@ibm.com>