Limit comment_history_delete.user.js to comment history pages only

[mjpieters]

The comment_history_delete script is active on all pages on every site, but this causes issues in the flag review queue; each comment you delete from the flag queue triggers an error dialog with Failed undefined: error.

The @match URLs are overly broad and should just be limited to:

// @match       *://*.stackoverflow.com/admin/users/*/post-comments
// ... etc.

[ArtOfCode-]

Heh, good point. I thought that was done, but I copied the match block from another script of mine and replaced the old matches.