AppInsights SDK / Azure OTel Distro Repro

Reproduces the issue mentioned in #2266 & #29398.

This repo provides a simple web application that allows adding/removing items to/from a list. Items are fetched from an API (Node/Express) and persisted to MongoDB.

1. Create .env files in frontend & backend. Copy from .env.template and add connection strings of the AI resources.
2. Start mongo container with docker compose up -d.
3. Install dependencies at /frontend and /backend with yarn.
4. Start applications at /frontend and /backend with yarn dev.

Repro-Steps for #29398

• Make sure 'disable cache' setting in unticked in your browser dev. tools
• Start web client, api and db as described above
• Add some items
• Trigger multiple calls of GET /products endpoint
  • Open Tanstack Query DevTools (small island symbol - bottom right corner)
  • Select ["products"], hit invalidate a few times to trigger a refetch of all 'products'
• Should see multiple 304's in your network tab
• Check application insights transaction search - shows successful requests with 304 response code
• Check Overview failed requests or Failures, there's a spike in failed requests
• When clicking on 'Top 3 response codes' and then '304', there are no available results