Remove default hash-offset for chassis-packet (sonic-net#19745)

Why I did it
Fixes sonic-net#19746

switch.json in swss docker sets the default hash offset to 0 for chassis-packet. The change was recently introduced via sonic-net#18912 which was supposed to be only for T0/T1. On chassis-packet, each asics needs to set an unique hash offset to set an unique offset for load balancing algorithm. The new change overwrites platform setting and resets the hash-offset to 0 on all asics. This breaks the ecmp load balancing algorithm on chassis-packet.

How I did it
Remove the default hash-offset setting for chassis-packet. This setting is provided by platform based on platform specific rules.

How to verify it
Run sonic-mgmt fib/test_fib.py

Signed-off-by: anamehra <anamehra@cisco.com>

dockers/docker-orchagent/switch.json.j2

@@ -26,8 +26,10 @@
             "ecmp_hash_seed": "{{ hash_seed_value }}",
             "lag_hash_seed": "{{ hash_seed_value }}",
             "fdb_aging_time": "600",
+{% if not DEVICE_METADATA.localhost.switch_type or DEVICE_METADATA.localhost.switch_type != "chassis-packet" %}
             "ecmp_hash_offset": "{{ ecmp_hash_offset_value }}",
             "lag_hash_offset": "{{ lag_hash_offset_value }}",
+{% endif %}
 {% if DEVICE_METADATA.localhost.type and "LeafRouter" in DEVICE_METADATA.localhost.type %}
             "ordered_ecmp": "true"
 {% else %}

src/sonic-config-engine/tests/sample_output/t2-switch-masic1.json

@@ -0,0 +1,11 @@
+[
+    {
+        "SWITCH_TABLE:switch": {
+            "ecmp_hash_seed": "26",
+            "lag_hash_seed": "26",
+            "fdb_aging_time": "600",
+            "ordered_ecmp": "false"
+        },
+        "OP": "SET"
+    }
+]

src/sonic-config-engine/tests/sample_output/t2-switch-masic3.json

@@ -0,0 +1,11 @@
+[
+    {
+        "SWITCH_TABLE:switch": {
+            "ecmp_hash_seed": "28",
+            "lag_hash_seed": "28",
+            "fdb_aging_time": "600",
+            "ordered_ecmp": "false"
+        },
+        "OP": "SET"
+    }
+]

src/sonic-config-engine/tests/test_j2files.py

@@ -47,6 +47,7 @@ def setUp(self):
         self.no_ip_helper_minigraph = os.path.join(self.test_dir, 't0-sample-no-ip-helper-graph.xml')
         self.nokia_ixr7250e_36x100g_t2_minigraph = os.path.join(self.test_dir, 'sample-nokia-ixr7250e-36x100g-t2-minigraph.xml')
         self.nokia_ixr7250e_36x400g_t2_minigraph = os.path.join(self.test_dir, 'sample-nokia-ixr7250e-36x400g-t2-minigraph.xml')
+        self.t2_sample_graph_chassis_packet = os.path.join(self.test_dir, 'sample-chassis-packet-lc-graph.xml')
         self.output_file = os.path.join(self.test_dir, 'output')
         os.environ["CFGGEN_UNIT_TESTING"] = "2"
 
@@ -753,6 +754,36 @@ def test_swss_switch_render_template_multi_asic(self):
             assert utils.cmp(sample_output_file, self.output_file), self.run_diff(sample_output_file, self.output_file)
         os.environ["NAMESPACE_ID"] = ""
 
+    def test_swss_switch_render_template_t2(self):
+        # verify the ECMP hash seed changes per namespace
+        switch_template = os.path.join(
+            self.test_dir, '..', '..', '..', 'dockers', 'docker-orchagent',
+            'switch.json.j2'
+        )
+        constants_yml = os.path.join(
+            self.test_dir, '..', '..', '..', 'files', 'image_config',
+            'constants', 'constants.yml'
+        )
+        test_list = {
+            "0": {
+                "namespace_id": "1",
+                "output": "t2-switch-masic1.json"
+            },
+            "1": {
+                "namespace_id": "3",
+                "output": "t2-switch-masic3.json"
+            },
+        }
+        for _, v in test_list.items():
+            os.environ["NAMESPACE_ID"] = v["namespace_id"]
+            argument = ["-m", self.t2_sample_graph_chassis_packet, "-y", constants_yml, "-t", switch_template]
+            sample_output_file = os.path.join(
+                self.test_dir, 'sample_output', v["output"]
+            )
+            self.run_script(argument, output_file=self.output_file)
+            assert utils.cmp(sample_output_file, self.output_file), self.run_diff(sample_output_file, self.output_file)
+        os.environ["NAMESPACE_ID"] = ""
+
     def test_ndppd_conf(self):
         conf_template = os.path.join(self.test_dir, "ndppd.conf.j2")
         vlan_interfaces_json = os.path.join(self.test_dir, "data", "ndppd", "vlan_interfaces.json")