Only disable Wi-Fi IP serving on specific interface, if available

Test: as follows
    - built
    - flashed
    - booted
    - runtest frameworks-net passes
Bug: 32163131
Bug: 62343300

Merged-In: Id8d9c3f67f7a850af69069abee86adfc62841b28
Merged-In: Iac19359fd8712fa6a135f31bed9f0da97b3f2977
Merged-In: I99b170ebacc4135d1a09ce1ec3d43f76c6765de4
Change-Id: Ifd9131bad20810ee24c9436d8c0df7a81fae11d5
(cherry picked from commit 218c226b0882640a351deb0dd945a30b8bc32fff)
2 files changed