MDL-58393 core: Remove firstname argument from emailconfirmation string

lang/en/moodle.php

@@ -609,7 +609,7 @@ $string['emailalreadysent'] = 'A password reset email has already been sent. Ple
 $string['emailactive'] = 'Email activated';
 $string['emailagain'] = 'Email (again)';
 $string['emailconfirm'] = 'Confirm your account';
-$string['emailconfirmation'] = 'Hi {$a->firstname},
+$string['emailconfirmation'] = 'Hi,
 
 A new account has been requested at \'{$a->sitename}\'
 using your email address.

lib/moodlelib.php

@@ -6583,7 +6583,6 @@ function send_confirmation_email($user, $confirmationurl = null) {
     $supportuser = core_user::get_support_user();
 
     $data = new stdClass();
-    $data->firstname = fullname($user);
     $data->sitename  = format_string($site->fullname);
     $data->admin     = generate_email_signoff();