Editor: remove the format_for_editor filter from `the_editor_content` after it...

Editor: remove the format_for_editor filter from `the_editor_content` after it runs as the next editor instance on the same page may not need it.

Props marcochiesi, azaozz.
Fixes #28403.
Built from https://develop.svn.wordpress.org/trunk@36062


git-svn-id: https://core.svn.wordpress.org/trunk@36027 1a063a9b-81f0-0310-95a4-ce76da25c4cd