refactor: Use @model.isNew instead of custom allowPassword

ui/core/app/components/form/account/password/index.hbs

@@ -63,7 +63,7 @@
     {{/if}}
   </form.input>
 
-  {{#if @allowPassword}}
+  {{#if @model.isNew}}
     <form.input
       @name="password"
       @type="password"

ui/core/app/templates/scopes/scope/auth-methods/auth-method/accounts/new.hbs

@@ -1,5 +1,4 @@
 <Form::Account::Password
-  @allowPassword={{true}}
   @model={{@model}}
   @submit={{route-action "save" @model}}
   @cancel={{route-action "cancel" @model}}