[Backport MB-39554 to 6.0.5] Index planner can create non-optimal index placement with multiple defer_buid = true indexes

When the index is created with defer_build = true, the sizing information for that index is not present.

When planner tries to place next index based on the current sizing information, planner assumes that the sizing information is present for the aforementioned index (because plasma can return non-zero data size). Note that memory for this index is still zero.

This can lead to non-optimal index placement.