[observability] add resources load failed ratio to code-browser

[mustard-mh]

Description

Add resources load failed ratio to code-browser

Overview

Faster Link

Related Issue(s)

Fixes #

How to test

See https://grafana.gitpod.io/d/PEu--An4k/vs-code-browser-overview-copy-huiwen?orgId=1

Their JSON should be similar (ignore id and panel positon etc)

Release Notes

NONE

Documentation

Werft options:

• [x] /werft with-preview
• [ ] /werft with-integration-tests=all Valid options are all, workspace, webapp, ide

[werft-gitpod-dev-com[bot]]

started the job as gitpod-build-hw-loaderr-observe.2 because the annotations in the pull request description changed (with .werft/ from main)

[akosyakov]

I don't think we should break by clusters, but have overall ratio.