Remove unused variables and resulting conditionals.

WifiTracker always is used in 'includeScans' mode, and is never used in
includeSaved mode. The former variable was not even referenced. The
original functionality of includeSaved true and includeScans mode was
for rendering the Saved Access Points page, which is now provided by
another utility. All calling apps currently filter out unreachable saved
networks they receive from WifiTracker.

Subsequent CLs will modify the updateAccessPointsLocked loop to simply
insert config data into existing APs, thus reducing the complexity of
thi class.

Bug: 68030053
Test: runtest --path
frameworks/base/packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/WifiTrackerTest.java

Change-Id: I7adb6de2e700c48543d7a43419527052f2909cc0