[API] Generator: Fixes order of arguments.clone

When updating the code generator for 8.x, the order of
`arguments.clone` in the generated code was changed. This would make
it so that we would modify the arguments before cloning them, which is
undesired.

Addresses #1727

elasticsearch-api/utils/thor/templates/_method_setup.erb

@@ -16,7 +16,6 @@
 # specific language governing permissions and limitations
 # under the License.
 %>
-<%= '  '*(@namespace_depth+4) %>arguments = arguments.clone
 <%- if @method_name == 'search' -%>
   arguments[:index] = UNDERSCORE_ALL if ! arguments[:index] && arguments[:type]
 <%- end -%>

elasticsearch-api/utils/thor/templates/method.erb

@@ -33,12 +33,14 @@ module Elasticsearch
   <%= '  '*(@namespace_depth+2) %>end
 <%- else -%>
   <%- if @method_name == 'get_field_mapping' %>
+    arguments = arguments.clone
     _fields = arguments.delete(:field) || arguments.delete(:fields)
     raise ArgumentError, "Required argument 'field' missing" unless _fields
   <%- else -%>
     <%- @required_parts.each do |required| %><%# Arguments -%>
       <%= '  '*(@namespace_depth+3) + "raise ArgumentError, \"Required argument '#{required}' missing\" unless arguments[:#{required}]" + "\n" -%>
     <%- end -%>
+    arguments = arguments.clone
     <%- end -%>
     headers = arguments.delete(:headers) || {}
     <%- #Body %>