Remove toggle "Turn on phone calls & SMS" from User Details of Main user

Admins should not be able to disable phone calls and SMS from the device owner.

Bug: 294846327
Test: atest UserDetailsSettingsTest
Change-Id: Ibb8532379c6e1e22fe45f2acb5191f8f6c7f3b0a

src/com/android/settings/users/UserDetailsSettings.java

@@ -376,7 +376,9 @@ public class UserDetailsSettings extends SettingsPreferenceFragment
             if (!Utils.isVoiceCapable(context)) { // no telephony
                 removePreference(KEY_ENABLE_TELEPHONY);
             }
-
+            if (mUserInfo.isMain()) {
+                removePreference(KEY_ENABLE_TELEPHONY);
+            }
             if (mUserInfo.isRestricted()) {
                 removePreference(KEY_ENABLE_TELEPHONY);
                 if (isNewUser) {