Add a mu-plugin to disable wp-autoupdates by filters

[tangrufus]

• I've read the guidelines for Contributing to Roots Projects
• This request isn't a duplicate of an existing request
• This is not a personal support request that should be posted on the Roots Discourse community

Add a mu-plugin to disable wp-autoupdates by filters

See: WordPress/wp-autoupdates#112

[retlehs]

since we set AUTOMATIC_UPDATER_DISABLED to true, it looks like we don't need to do anything here?

per @joshuafredrickson on roots slack:

// Disable plugins auto-update UI elements.
add_filter('plugins_auto_update_enabled', '__return_false');
// Disable themes auto-update UI elements.
add_filter('themes_auto_update_enabled', '__return_false');

is not necessary on a bedrock install, and

it removes the auto-update ui elements as well

i might be mis-understanding this issue though