Azure.Sdk.Tools.SwaggerApiParser_1.0.4-dev.20221216.1

Add load-testing to list of valid sample slugs (#4940)

`azure-load-testing` is an approved product slug in https://review.docs.microsoft.com/help/contribute/metadata-taxonomies?branch=main#product but is not present in the SampleMetadata.ps1 file. Adding it here as pipelines are failing due to this