Settings reset should not apply to entire network

[pdclark]

From https://wordpress.org/support/topic/reset-customizer-settings-resets-all-sites-in-a-network?replies=1

When doing a reset for a single site in a WordPress network (by going to "Settings" > "Styles" > "Reset Customizer Settings"), every sites in the WordPress network is being reset.

This is a pretty serious bug, since any site in the network can reset all style settings for the entire network.