Don't link temporary account and named account in newusers log

Why:
* When a temporary account creates a named account, the 'newusers'
  log currently links the temporary account username and the new
  named account.
* This is an issue because temporary accounts are intended to be
  anonymous and there is no path for a temporary account to
  link their contributions to their new account. As such, there
  should be no link between them.

What:
* Update AuthManager::continueAccountCreation to only mark the
  performer of the 'newusers' log entry as the creator account
  if the creator is named.

Bug: T364716
Change-Id: Ib95374949c5c72c9f7ee665943c16d177f2e31c0

includes/auth/AuthManager.php

@@ -1665,12 +1665,12 @@ public function continueAccountCreation( array $reqs ) {
 
  // Log the creation
  if ( $this->config->get( MainConfigNames::NewUserLog ) ) {
- $isAnon = $creator->isAnon();
+ $isNamed = $creator->isNamed();
  $logEntry = new \ManualLogEntry(
  'newusers',
- $logSubtype ?: ( $isAnon ? 'create' : 'create2' )
+ $logSubtype ?: ( $isNamed ? 'create2' : 'create' )
  );
- $logEntry->setPerformer( $isAnon ? $user : $creator );
+ $logEntry->setPerformer( $isNamed ? $creator : $user );
  $logEntry->setTarget( $user->getUserPage() );
  /** @var CreationReasonAuthenticationRequest $req */
  $req = AuthenticationRequest::getRequestByClass(