Remove Smart Lock developer options

This CL removes the temporary developer options that were available to
switch Smart Lock to and from Extend Unlock mode. The Q release will
switch to Extend Unlock permanently, and these options are no longer
needed.

Bug: 120871688
Test: Manually tested that Extend Unlock mode works as expected
Change-Id: I437def3bf750e29e5ade7ba54856cfa74525a67d