### What?
This PR fixes an issue while using `text` & `number` fields with
`hasMany: true` where the last entry would be unreachable, and thus
undeletable, because the `transformForWrite` function did not track
these rows for deletion. This causes values that should've been deleted
to remain in the edit view form, as well as the db, after a submission.
This PR also properly threads the placeholder value from
`admin.placeholder` to `text` & `number` `hasMany: true` fields.
### Why?
To remove rows from the db when a submission is made where these fields
are empty arrays, and to properly show an appropriate placeholder when
one is set in config.
### How?
Adjusting `transformForWrite` and the `traverseFields` to keep track of
rows for deletion.
Fixes#11781
Before:
[Editing---Post-dbpg-before--Payload.webm](https://github.com/user-attachments/assets/5ba1708a-2672-4b36-ac68-05212f3aa6cb)
After:
[Editing---Post--dbpg-hasmany-after-Payload.webm](https://github.com/user-attachments/assets/1292e998-83ff-49d0-aa86-6199be319937)
bd512f1eda