Site monitoring function fails to deploy without `local_files_dir`

Description

This module makes use of the gcp-site-monitoring module which in turns make use of gcp-function. gcp-function has a known issue when the local_files_dir is not set, the CI apply job fails. See here for more information.

At the moment, the gcp-cloud-run-app module does not expose nor pass the local_files_dir variable value to the site monitoring module. As a result, users cannot apply changes using CI when the authentication_proxy is enabled.

The "correct" solution to this is unclear see here.

Acceptance criteria

• local_files_dir is passed through to the gcp-site-monitoring module call to workaround this issue.

Links/references

https://gitlab.developers.cam.ac.uk/uis/devops/digital-admissions/admissions-portal/ap-deployment/-/issues/242#note_748786