[Arista] Add Arista-7050CX3-32S-C28S4 to generic_config_updater (#3935)

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#### What I did
Set ASIC of Arista-7050CX3-32S-C28S4 to td3.
#### How I did it

#### How to verify it

#### Previous command output (if the output of a command-line utility has changed)

#### New command output (if the output of a command-line utility has changed)

Author: mssonicbld

generic_config_updater/gcu_field_operation_validators.conf.json

@@ -32,7 +32,7 @@
                 "th4": [ "Nokia-IXR7220-H4-64D", "Nokia-IXR7220-H4-32D" ],
                 "th5": [ "Nokia-IXR7220-H5-64D", "Arista-7060X6-64DE", "Arista-7060X6-64PE" ],
                 "td2": [ "Force10-S6000", "Force10-S6000-Q24S32", "Arista-7050-QX32", "Arista-7050-QX-32S", "Nexus-3164", "Arista-7050QX32S-Q32" ],
-                "td3": [ "Arista-7050CX3-32S-C32", "Arista-7050CX3-32S-D48C8" ],
+                "td3": [ "Arista-7050CX3-32S-C32", "Arista-7050CX3-32S-D48C8", "Arista-7050CX3-32S-C28S4" ],
                 "j2c+": [ "Nokia-IXR7250E-36x100G", "Nokia-IXR7250E-36x400G" ]
             }
 	}