Remove redundant initialization in Table::allocate

[JaySpruce]

Objective

Table::allocate zero-initializes ticks immediately after reserving a new row in its columns, but this isn't really necessary since either Column::initialize_from_unchecked (in Tables::move_row) or Column::initialize (in BundleInfo::write_components) is always called before they're assumed to be initialized.

Solution

Remove the initialization in Table::allocate (and update Column::initialize to expect to actually initialize them).

Testing

Pretty good: