Revert "Unhide enable_apps carrier config key."

This reverts commit 4793b28d3f2a65492aa7049c5e6e77c1cdbbb1a3.

Reason for revert: This is not intended as a public API.

Bug: 62907095
Test: make
Change-Id: Id79f91c72eac3929fa5ee7ac1cdd9df8671a1eb1
(cherry picked from commit f47a426206cd89d49df8369eaa98a685365a62ed)
diff --git a/telephony/java/android/telephony/CarrierConfigManager.java b/telephony/java/android/telephony/CarrierConfigManager.java
index c79eec0..8b8310f 100644
--- a/telephony/java/android/telephony/CarrierConfigManager.java
+++ b/telephony/java/android/telephony/CarrierConfigManager.java
@@ -951,6 +951,8 @@
      * If user has explicitly disabled some packages in the list, won't re-enable.
      * Other carrier specific apps which are not in this list may be disabled for current carrier,
      * and only be re-enabled when this config for another carrier includes it.
+     *
+     * @hide
      */
     public static final String KEY_ENABLE_APPS_STRING_ARRAY = "enable_apps_string_array";