[Test Improvement] Move common setup tasks to the views base test class

Problem/Motivation

In AjaxAddCartViewsRemoveButtonTest every test has a common setup task:

$this->drupalLogin($this->drupalCreateUser([
  'access cart',
]));

Such common task can be moved inside the base test class.

Proposed resolution

The creation of the user should be moved inside AjaxAddCartViewsTestBase.

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A