Bundled Themes: Twenty Twenty content font CSS selector is too important.

This makes the font family selector for `entry-content` less specific and thus easier to override.

Props alexandreb3, larrach, audrasjb.
Fixes #49318.
Built from https://develop.svn.wordpress.org/trunk@47133


git-svn-id: https://core.svn.wordpress.org/trunk@46933 1a063a9b-81f0-0310-95a4-ce76da25c4cd