Add dotnet-api product slug to sample metadata script (#7316)

Co-authored-by: Anne Thompson <[email protected]>

Author: azure-sdk

eng/common/scripts/Test-SampleMetadata.ps1

@@ -330,6 +330,7 @@ begin {
         "blazor-webassembly",
         "common-data-service",
         "customer-voice",
+        "dotnet-api",
         "dotnet-core",
         "dotnet-standard",
         "document-intelligence",