ExternalIdNotes: Make constructor and load() method private

ExternalIdNotes should either be created by the factories or the static
load methods. The constructor and the load() method were not private
because ExternalIdsUpdate needed them, but now after ExternalIdsUpdate
was removed we can make them private.

Change-Id: I19c8b140e60d8685595d831724d14cac075a578d
Signed-off-by: Edwin Kempin <ekempin@google.com>

java/com/google/gerrit/server/account/externalids/ExternalIdNotes.java

@@ -171,7 +171,7 @@ public class ExternalIdNotes extends VersionedMetaData {
   private Runnable afterReadRevision;
   private boolean readOnly = false;
 
-  ExternalIdNotes(
+  private ExternalIdNotes(
       ExternalIdCache externalIdCache,
       @Nullable AccountCache accountCache,
       Repository allUsersRepo) {
@@ -205,7 +205,7 @@ public class ExternalIdNotes extends VersionedMetaData {
    *
    * @return {@link ExternalIdNotes} instance for chaining
    */
-  ExternalIdNotes load() throws IOException, ConfigInvalidException {
+  private ExternalIdNotes load() throws IOException, ConfigInvalidException {
     load(repo);
     return this;
   }