Update apiProperties.json (#3131)

Removing x-api-key from apiProperties.json file

certified-connectors/TxtSync/apiProperties.json

@@ -34,7 +34,7 @@
         "title": "APIKeyHeaderPolicy",
         "parameters": {
           "x-ms-apimTemplateParameter.name": "x-api-key",
-          "x-ms-apimTemplateParameter.value": "M3Yf9L0njL8eL9ukphahq9zk5LFRIOvn2fT4BcmV",
+          "x-ms-apimTemplateParameter.value": "dummy-value",
           "x-ms-apimTemplateParameter.existsAction": "override",
           "x-ms-apimTemplate-policySection": "Request"
         }