[Kitchen test] Add Ubuntu Os for C_state Install phase tests

Author: Himani Anil Deshpande

cookbooks/aws-parallelcluster-platform/test/controls/c_states_spec.rb

@@ -3,16 +3,13 @@
   title 'Check the configuration to disable c states'
   only_if { !os_properties.on_docker? && os_properties.x86? }
 
-  if os_properties.ubuntu2004?
-    describe file('/etc/default/grub') do
-      it { should exist }
-      its('content') { should match(/processor.max_cstate=1/) }
-      its('content') { should match(/intel_idle.max_cstate=1/) }
-    end
-    describe file('/boot/grub/grub.cfg') do
-      it { should exist }
-      its('content') { should match(/processor.max_cstate=1/) }
-      its('content') { should match(/intel_idle.max_cstate=1/) }
+  if os_properties.ubuntu?
+    %w(/etc/default/grub /boot/grub/grub.cfg).each do |file_path|
+      describe file(file_path) do
+        it { should exist }
+        its('content') { should match(/processor.max_cstate=1/) }
+        its('content') { should match(/intel_idle.max_cstate=1/) }
+      end
     end
   else
     describe bash('cpupower idle-info') do