Fix Rubocop Performance/StringInclude cop

Author: mhashizume

spec/acceptance/tests/mounted_spec.rb

@@ -15,7 +15,7 @@
         MountUtils.create_filesystem(agent, name)
 
         step 'create a mount with puppet (mounted)'
-        args = if %r{aix}.match?(agent['platform'])
+        args = if agent['platform'].include?('aix')
                  ['ensure=mounted',
                   "fstype=#{fs_type}",
                   "options='log=/dev/hd8'",

spec/spec_helper_acceptance.rb

@@ -31,7 +31,7 @@
     # umount disk image
     on(agent, "umount /#{name}", acceptable_exit_codes: (0..254))
     # delete disk image
-    if %r{aix}.match?(agent['platform'])
+    if agent['platform'].include?('aix')
       on(agent, "rmlv -f #{name}", acceptable_exit_codes: (0..254))
     else
       on(agent, "rm /tmp/#{name}", acceptable_exit_codes: (0..254))