Passing array args broken in XML backend

Bug report

Required Info:

• Operating System:
  • MacOS 12.3
• Installation type:
  • source
• Version or commit hash:
  • humble

Steps to reproduce issue

<launch>
    <arg name="int_array" default="1,2,3,4,5,6,7" />

	<node pkg="test_node" name="test_node" exec="test_node">
		<param name="int_array"  value-sep="," value="$(var int_array)" />
	</node>
</launch>

Expected behavior

Should correctly pass the arg int_array as integer array to the node.

Actual behavior

Passes ['1,2,3,4,5,6,7'] instead:

[test_node-1] libc++abi: terminating with uncaught exception of type rclcpp::exceptions::InvalidParameterTypeException: parameter 'ids_to_ignore' has invalid type: Wrong parameter type, parameter {int_array} is of type {integer_array}, setting it to {string_array} is not allowed.```