Update include_macsec flag if type is SpineRouter (sonic-net#11141)

Add the support to enable macsec when type is SpineRouter

files/build_templates/init_cfg.json.j2

@@ -46,7 +46,7 @@
 {%- if include_p4rt == "y" %}{% do features.append(("p4rt", "enabled", false, "enabled")) %}{% endif %}
 {%- if include_restapi == "y" %}{% do features.append(("restapi", "enabled", false, "enabled")) %}{% endif %}
 {%- if include_sflow == "y" %}{% do features.append(("sflow", "disabled", false, "enabled")) %}{% endif %}
-{%- if include_macsec == "y" %}{% do features.append(("macsec", "disabled", false, "enabled")) %}{% endif %}
+{%- if include_macsec == "y" %}{% do features.append(("macsec", "{% if 'type' in DEVICE_METADATA['localhost'] and DEVICE_METADATA['localhost']['type'] == 'SpineRouter' %}enabled{% else %}disabled{% endif %}", false, "enabled")) %}{% endif %}
 {%- if include_system_telemetry == "y" %}{% do features.append(("telemetry", "enabled", true, "enabled")) %}{% endif %}
     "FEATURE": {
 {# has_timer field if set, will start the feature systemd .timer unit instead of .service unit #}