fix: Update function directory in load request to use /home/site/wwwroot

[gavin-aguiar]

Description

This fixes a bug introduced in #1446.

For function apps using FWPC > 1 and using blueprints, the second worker does not get the metadata request. In the load request, the worker uses the function directory sent from the host. This works for functions apps without blueprints since the func dir is always /home/site/wwwroot. For blueprints, the function dir is /home/site/wwwroot/<blueprint_dir>. So in the load request, the worker tries to find function_app.py in /home/site/wwwroot/<blueprint_dir> and it fails indexing.
Fix is to always use /home/site/wwwroot for v2 programming model

Fixes #

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