Dismissed notices re-appear before they are supposed to

[brianhogg]

Reproduction Steps

1. On WPEngine (and likely other) hosting, dismiss the NGINX notice. This should remind in 10000 days.
2. A few days later, login.

Expected Behavior

Notice does not appear.

Actual Behavior

Notice appears.

This issue has be recreated:

• [ ] Locally
• [ ] On a staging site
• [ ] On a production website
• [ ] With only LifterLMS and a default theme

[brianhogg]

Because the delay is set as a transient, I believe the transient is being removed. As per the explanation of transients:

"Everyone seems to misunderstand how transient expiration works, so the long and short of it is: transient expiration times are a maximum time. There is no minimum age. Transients might disappear one second after you set them, or 24 hours, but they will never be around after the expiration time."

Instead we can use options that will not just disappear randomly.

[brianhogg]

As a workaround for the media protection notice, this filter can be added:

add_filter( "llms_admin_notice_using_nginx", "__return_false")