class RuboCop::Cop::Chef::Style::NegatingOnlyIf

Instead of using only_if conditionals with ! to negate the returned value, use not_if which is easier to read

@example

### incorrect
package 'legacy-sysv-deps' do
  only_if { !systemd }
end

### correct
package 'legacy-sysv-deps' do
  not_if { systemd }
end