Revert "Revert "Update default cable len to 0m for TD2"" (#8354)

* Update default cable len to 0m for TD2 (#8298)
* Update sonic-cfggen tests with the correct cable len

Signed-off-by: Neetha John <nejo@microsoft.com>

As part of the buffer reclamation efforts for TD2, setting the default cable len to 0m which means unused ports will have a cable len of 0m.

Why I did it
To align with the changes in Azure/sonic-swss#1830

How to verify it
- With the default cable len set to 0m and the associated changes in swss, CABLE_LENGTH table had '0m' set for unused ports and accordingly more space was reserved for the shared pool
- Cfggen tests passed with the cable len update

device/arista/x86_64-arista_7050_qx32/Arista-7050-QX32/buffers_defaults_t0.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/arista/x86_64-arista_7050_qx32/Arista-7050-QX32/buffers_defaults_t1.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/arista/x86_64-arista_7050_qx32s/Arista-7050QX-32S-S4Q31/buffers_defaults_t0.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/arista/x86_64-arista_7050_qx32s/Arista-7050QX-32S-S4Q31/buffers_defaults_t1.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/arista/x86_64-arista_7050_qx32s/Arista-7050QX32S-Q32/buffers_defaults_t0.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/arista/x86_64-arista_7050_qx32s/Arista-7050QX32S-Q32/buffers_defaults_t1.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/dell/x86_64-dell_s6000_s1220-r0/Force10-S6000/buffers_defaults_def.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/dell/x86_64-dell_s6000_s1220-r0/Force10-S6000/buffers_defaults_t0.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

device/dell/x86_64-dell_s6000_s1220-r0/Force10-S6000/buffers_defaults_t1.j2

@@ -1,4 +1,4 @@
-{%- set default_cable = '300m' %}
+{%- set default_cable = '0m' %}
 
 {%- macro generate_port_lists(PORT_ALL) %}
     {# Generate list of ports #}

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

@@ -393,14 +393,14 @@ class TestMultiNpuCfgGen(TestCase):
             output['CABLE_LENGTH'],
             {
                 'AZURE': {
-                    'Ethernet8': '300m',
+                    'Ethernet8': '0m',
                     'Ethernet0': '300m',
                     'Ethernet4': '300m',
                     'Ethernet-BP4': '5m',
                     'Ethernet-BP0': '5m',
                     'Ethernet-BP12': '5m',
                     'Ethernet-BP8': '5m',
-                    'Ethernet12': '300m'
+                    'Ethernet12': '0m'
                 }
             }
         )