Fix fr3's ros2_control.xacro to load fr3_gripper controller

[devika-dudo]

In the robots/common/franks_arm.ros2_control.xacro for adding fingers into the ros2_control has a line like this
<xacro:if value="${gazebo and hand}"> <xacro:configure_joint joint_name="${arm_prefix}${arm_id}_finger_joint1" initial_position="0.0" /> </xacro:if>

but i wasnt able to load the fr3_gripper --- there was an error about missing interfaces of finger_joint_2 so once i changed the xacro to this i was able to load the fr3_gripper.
is this a fix??

<xacro:if value="${gazebo and hand}"> <xacro:configure_joint joint_name="${arm_id}_finger_joint1" initial_position="0.0" /> <xacro:configure_joint joint_name="${arm_id}_finger_joint2" initial_position="0.0" /> </xacro:if>