AccountConfig: Remove unneeded validation of preferred email

AccountConfig was validating the preferred email and generated a
validation error if it was invalid, however the validation errors were
always ignored and never accessed.

Instead the validation of the preferred email is done in
AccountValidator. Here the validation only results into an error if the
preferred email was changed to an invalid email, but not if the email
already was invalid and stayed unchanged. This is something that
AccountConfig can't do since it doesn't know about the previous account
state.

Change-Id: I656a4f405bda44c1a4194439061dc73c3c0bea44
Signed-off-by: Edwin Kempin <ekempin@google.com>

java/com/google/gerrit/server/git/validators/AccountValidator.java

@@ -90,7 +90,7 @@ public class AccountValidator {
   private Optional<Account> loadAccount(Account.Id accountId, RevWalk rw, ObjectId commit)
       throws IOException, ConfigInvalidException {
     rw.reset();
-    AccountConfig accountConfig = new AccountConfig(null, accountId);
+    AccountConfig accountConfig = new AccountConfig(accountId);
     accountConfig.load(rw, commit);
     return accountConfig.getLoadedAccount();
   }