Disable any graph object in bottom pane

Version: 2022b

Type: Features

Category: Data Handling

Subcategory: Worksheet

Jira: ORG-25131

System register variable @WSB (=1 by default) is added, and no graph object will be shown in the bottom when workbook is splitting.

Also, no gap will be shown at the bottom pane any more. It should be shown only at the above pane.