This isn't actually a Lever setting, but a Google Calendar setting!
It's an account-level setting for your entire G Suite Domain, meaning this must be changed by an administrator so feel free to share with someone on your team who has access to this page:.
Specifically at the following link:
There is an option as shown below:
Once you turn that off, you will no longer see Google Hangout links to your calendar invites unless you add them.