Remove "Show password" in Security page

"Show password" will be moved in Settings > Privacy.
Since each of things should only exist in one place,
we remove it in Security page.

Test: visual
Bug: 116628158
Change-Id: I9f9083b88d7a20faa9bd28ded2cf8c3b9a5622fd

src/com/android/settings/security/SecuritySettings.java

@@ -108,7 +108,6 @@ public class SecuritySettings extends DashboardFragment {
         controllers.add(new ManageTrustAgentsPreferenceController(context));
         controllers.add(new ScreenPinningPreferenceController(context));
         controllers.add(new SimLockPreferenceController(context));
-        controllers.add(new ShowPasswordPreferenceController(context));
         controllers.add(new EncryptionStatusPreferenceController(context,
                 PREF_KEY_ENCRYPTION_SECURITY_PAGE));
         controllers.add(new TrustAgentListPreferenceController(context, host, lifecycle));