osu: remove calls to deprecated APIs

The hidden APIs WifiManager#addPasspointManagmentObject and
WifiManager#addPasspointManagementObject will removed, so remove
all callsites.

The OSU app is still under developement and is not included
in any device builds.  However, it is being built by the Treehugger
for generic AOSP builds.

So fix it to allow the API removal CLs to be submitted.

Bug: 32509661
Test: None
Change-Id: Ic405695ee8edfd0c08b831834797f163fe445595