If young-gc fails (promotion-failure), Serial upgrades to full-gc directly, without leaving the safepoint, so the incremental-collection-failure is never exposed externally.

Remove all methods related to this field.

Additionally, the decision to use from-space if !collection_attempt_is_safe() && !_eden_space->is_empty() can cause heap too full to be handled properly by full-gc, so the support alloc-in-from-space is also removed.