[http-client-csharp] Operation name conflicts

There are 2 operations names [list](https://github.com/Azure/azure-rest-api-specs/blob/706f864d76b3969e919e006bc1c9c2a923ce1280/specification/billingbenefits/BillingBenefits.Management/back-compatible.tsp#L17) and [listAll](https://github.com/Azure/azure-rest-api-specs/blob/706f864d76b3969e919e006bc1c9c2a923ce1280/specification/billingbenefits/BillingBenefits.Management/back-compatible.tsp#L8), they both got renamed to GetAll in [MTG](https://github.com/microsoft/typespec/blob/f8aa6f8589552f4e6bfc6b99f491c0870f399279/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientProvider.cs#L192-L208). And it causes unexpected override during createRequest method and pagination model.