Remove configurations that are not used anywhere

Problem/Motivation

Some of the Drupal settings in the configuration form are not used anywhere in the code. If not needed, these settings can be removed.

The only variables used by VWO script are:
- Account Id
- Test Settings Download Timeout
see code https://git.drupalcode.org/project/vwo/-/blob/8.x-1.x/vwo.module#L159

The following variables are not used anywhere:

1. Async options. There is a comment here https://git.drupalcode.org/project/vwo/-/blob/8.x-1.x/src/Form/Settings.... stating that synchronous code is not implemented in D8, if that is the case, we don't need the option to choose sync mode.

2. Test library download timeout, see form https://git.drupalcode.org/project/vwo/-/blob/8.x-1.x/src/Form/Settings....

3. jQuery options, see form https://git.drupalcode.org/project/vwo/-/blob/8.x-1.x/src/Form/Settings....

The following Drupal settings are not used anywhere:
- id
- timeout_library
- timeout_setting
- usejquery
- testnull

All drupalSetttings that are added to the page are not used anywhere, see https://git.drupalcode.org/project/vwo/-/blob/8.x-1.x/vwo.module#L167

Proposed solution

If the settings are required by the VWO script, then they need to be added in https://git.drupalcode.org/project/vwo/-/blob/8.x-1.x/vwo.module#L158 the same way the setting for timeout_setting is being set.
If the settings no longer need to be in the configuration form, they can be removed.
Also need to be removed from config install and config schema.