Toggling Pending Review reveals "Move to trash" button

[aduth]

Issue Overview

When toggling "Pending review" on a new post, the "Move to trash" button is shown, despite the post not yet having been saved.

Steps to Reproduce

1. Navigate to Gutenberg > New Post
2. In Settings, toggle Pending review

Expected Behavior

The pending review toggles, but otherwise no changes to display.

Current Behavior

The pending review toggles and reveals a "Move to trash" button. Even when toggling back off, the button remains.

Related Issue

Suspected to be a regression of #1967, specifically in that post "New"-ness is determined by its status being auto-draft. In this behavior, I believe because the status is changing from "Pending", then back to "Draft" explicitly, the editor no longer considers the post to be new.