[automerger skipped] Cherry-pick: Remove usage of WifiConfiguration#setProxy() am: b2b5cb6ab8 am: 90ca106cc2 -s ours am: a20e6f2607 -s ours am: b68641e1a1 -s ours

am skip reason: Change-Id I4e1bff220af11e6ce9e6d8553ad9c3ca9db1c5f7 with SHA-1 458c5a294e is in history

Original change: https://android-review.googlesource.com/c/platform/packages/apps/ManagedProvisioning/+/1358103

Change-Id: I566efd0fe6ff06328390a45da12657fa20d723c0