Fix spelling of `ADITIONAL_VENV_PACKAGES`

This preserved `ADITIONAL_VENV_PACKAGES` as an input for backwards
compatiblity, but takes `ADDITIONAL_VENV_PACKAGES` with priority.

Fixes spelling in comment.

Related-Bug: #2046936
Change-Id: I84151d8f71b12da134e8fb9dbf3ae30f2a171fe2
1 file changed