refs #15246 [instance/fid_bbi] use default authenticator login template.

themes/fid_bbi/templates/Auth/AbstractBase/login.phtml

-<?php $account = $this->auth()->getManager(); ?>
-<?php $sessionInitiator = $account->getSessionInitiator($this->serverUrl($this->url('myresearch-home'))); ?>
-<?php if (!$sessionInitiator): // display default login form if no login URL provided ?>
-  <form method="post" action="<?=$this->url('myresearch-home')?>" name="loginForm" class="form-login">
-    <?=$this->auth()->getLoginFields()?>
-    <input type="hidden" name="auth_method" value="<?=$account->getAuthMethod()?>">
-    <input type="hidden" name="csrf" value="<?=$this->escapeHtmlAttr($account->getCsrfHash())?>" />
-    <div class="form-group">
-      <input class="btn btn-primary" type="submit" name="processLogin" value="<?=$this->transEsc('Login')?>">
-      <?php /*supportsCreation currently doesn't work in FidCore module cf. #15245
-          if ($account->supportsCreation('externalauth')): */?>
-          <a data-lightbox href="<?=$this->url('feedback-form')?>?id=RegistrationRequest"><?=$this->transEsc('Create New Account')?></a>
-      <?php /*endif; */?>
-      <?php if ($account->supportsRecovery()): ?>
-        <a class="btn btn-link" href="<?=$this->url('myresearch-recover') ?>?auth_method=<?=$account->getAuthMethod()?>"><?=$this->transEsc('Forgot Password')?></a>
-      <?php endif; ?>
-    </div>
-  </form>
-<?php else: ?>
-  <a href="<?=$this->escapeHtmlAttr($sessionInitiator)?>" class="btn btn-link" data-lightbox-ignore><?=$this->transEsc("Institutional Login")?></a>
-<?php endif; ?>