[1.5.x] Fixed #13794 -- Fixed to_field usage in BaseInlineFormSet.

Thanks sebastien at clarisys.fr for the report and gautier
for the patch.

Backport of 5e2c4a4bd1 from master
[1.5.x] Revert "Fixed #13794 -- Fixed to_field usage in BaseInlineFormSet."

This reverts commit 4ae68f677b3348765d8649d8b57beffa18fe8d3d.

stable/1.5.x branch is in security-fixes-only mode.