ChangeFeedProcessor: Fixes a bug properly when dealing with Legacy lease incremental documents that do not have a Mode property#4426

ealsur merged 5 commits intomasterAzure/azure-cosmos-dotnet-v3:masterfrom

users/philipthomas-MSFT/changefeedprocessorbuilder-throws-exception-for-changefeedmode-on-3.39.0-4423Azure/azure-cosmos-dotnet-v3:users/philipthomas-MSFT/changefeedprocessorbuilder-throws-exception-for-changefeedmode-on-3.39.0-4423Copy head branch name to clipboard