Revert "[Wi-Fi] Apply WifiTrackerLib objects in Wi-Fi Slice"

This reverts commit 7b1aded2a6.

Reason for revert: Settings is crashing for WiFi selection in SetupWizard on wembley

Bug: 161434533
Change-Id: I1d90e9bae1b31862fba674db0d7497e43f987a7f
Test: Locally reverted, reflashed, and was able to select WiFi without Settings crashing.
Exempt-From-Owner-Approval: Revert to clear up P0 while all owners are outside of work hours

tests/robotests/src/com/android/settings/testutils/shadow/ShadowWifiManager.java

@@ -18,7 +18,6 @@ package com.android.settings.testutils.shadow;
 
 import static org.robolectric.RuntimeEnvironment.application;
 
-import android.net.wifi.ScanResult;
 import android.net.wifi.SoftApConfiguration;
 import android.net.wifi.WifiConfiguration;
 import android.net.wifi.WifiManager;
@@ -82,11 +81,6 @@ public class ShadowWifiManager extends org.robolectric.shadows.ShadowWifiManager
         return false;
     }
 
-    @Implementation
-    protected List<ScanResult> getScanResults() {
-        return new ArrayList<ScanResult>();
-    }
-
     public static ShadowWifiManager get() {
         return Shadow.extract(application.getSystemService(WifiManager.class));
     }