Apply a proper fix to WebFunctionsManager.CreateOrUpdate for metadata refresh bug

Currently a tactical hack exists in the [WebFunctionsManager.CreateOrUpdate](https://github.com/Azure/azure-functions-host/blob/ba3e9ef990a9a5ebacaf47bbc3a71ed5f661e8ea/src/WebJobs.Script.WebHost/Management/WebFunctionsManager.cs#L86) where we're not using the general IFunctionMetadataManager service to get metadata. This is due to some deep issues with worker indexing + metadata refresh that need to be fixed by larger scale refactorings.

So temporarily there's a hack in place in this method to get the majority of scenarios working again, while we work on a proper fix. Prior to this fix, this create API was nearly 100% broken, affecting mainly portal development scenarios.

Start in src/WebJobs.Script.WebHost/Management/WebFunctionsManager.cs at CreateOrUpdate, then inspect the IFunctionMetadataManager usage and the worker indexing and metadata refresh issues described in the report. The fix is complete when CreateOrUpdate no longer relies on the tactical metadata hack and the affected create API scenarios work through the proper metadata path.

Written by the indexing model from the issue text.