Address comment from aosp/1232197

1. Call maybeRemoveDeprecatedUpstreams from Tethering rather than inside
PrivateAddressCoordinator because the building logic of this method based
on implementation details of Tethering.
2. Fix typo

Bug: 130879722
Test: -build, flash, boot
      -atest TetheringTests

Merged-In: I7584253b728bc17fc648fc19e492ca9f7ad2ff46
Change-Id: I7584253b728bc17fc648fc19e492ca9f7ad2ff46