multi_buffer: Pre-allocate IDs when editing (#36819)

Something I came across when looking at `edit_internal`. Potentially
saves multiple re-allocations on an edit

Release Notes:

- N/A
dd6fce6d4etidely committed on 8/24/2025, 6:59:32 AM· committed by GitHubparentde5f87e
1 file changedLine totals unavailable