fix: ignore TermOpen event in terminal previewer

[anonymousgrasshopper]

Description

When a terminal previewer is created, the TermOpen event is registered. This can mess up with user autcomds.
I think the event should be ignored to prevent this.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)