[Settings] Code refactor - remove unused import lines

Remove some unused import lines within source code based on
https://source.android.com/setup/contribute/code-style

Bug: 182867979
Test: build pass
Change-Id: I76dbcfa9e5b435b2838401dfee15b12f472d07d0

src/com/android/settings/wifi/slice/ContextualWifiScanWorker.java

@@ -20,8 +20,6 @@ import android.content.Context;
 import android.net.Uri;
 import android.os.SystemClock;
 
-import com.android.settings.slices.SliceBackgroundWorker;
-
 /**
  * {@link SliceBackgroundWorker} for Wi-Fi, used by {@link ContextualWifiSlice}.
  */