This sets the fallback icon theme to the current(system default) icon theme before
launcher specific themes are applied
And removes `Inherits` line of multimc/legacy icon theme because it can end up making it
inherit a default theme set from /usr/share/icons/default/index.theme
instead of the user configured theme (probably a qt bug?)
Signed-off-by: leia uwu <leia@tutamail.com>