test/crimson/seastore/test_transaction_manager: the scatter_allocation case shouldn't submit the trans
In scatter_allocation, an extent is split into several
small ones, and the last allocation is supposed to fail,
in which case, the small extents that belong to the same
allocation wouldn't be attached to the parent lba leaf
node. Sumitting the transaction would trigger assertions,
and is not consistent with the behavior of nornal crimson
OSDs.