Unsuppress deprecated IoT operations

As customers move from V1 (which exposes these operations), to V2, they
may not be able to move to the recommended operations because of
external constraints such as IAM policies that only allow certain
operations.

Note: IoT is not the only service that has suppressed operations. We
will unsuppress them on need basis to avoid cluttering clients
unnecessarily.

Author: dagnir

services/iot/src/main/resources/codegen-resources/customization.config

@@ -44,12 +44,6 @@
         "listAuditFindings",
         "listV2LoggingLevels"
     ],
-    "deprecatedOperations": [
-        "AttachPrincipalPolicy",
-        "DetachPrincipalPolicy",
-        "ListPolicyPrincipals",
-        "ListPrincipalPolicies"
-    ],
     "shapeModifiers": {
         "AssetPropertyVariant": {
             "union": true