[oidc] Fix the HEAD method call that checks reachability

[nandajavarma]

Description

We are checking connectivity with the root of issuer, which might fail if the root is not serving anything. We sometimes get a 503 on this endpoint. So this PR replaces it to call .well-known/openid-configuration endpoint which should exist if it is a valid OIDC service

Related Issue(s)

Fixes #

How to test

Documentation

Preview status

gitpod:summary

Build Options

Build

• /werft with-werft
  Run the build with werft instead of GHA
• leeway-no-cache
• /werft no-test
  Run Leeway with --dont-test

Publish

• /werft publish-to-npm
• /werft publish-to-jb-marketplace

Installer

• analytics=segment
• with-dedicated-emulation
• workspace-feature-flags
  Add desired feature flags to the end of the line above, space separated

Preview Environment / Integration Tests

• /werft with-local-preview
  If enabled this will build install/preview
• /werft with-preview
• /werft with-large-vm
• /werft with-gce-vm
  If enabled this will create the environment on GCE infra
• /werft preemptible
  Saves cost. Untick this only if you're really sure you need a non-preemtible machine.
• with-integration-tests=all
  Valid options are all, workspace, webapp, ide, jetbrains, vscode, ssh. If enabled, with-preview and with-large-vm will be enabled.
• with-monitoring

/hold

[geropl]

Creating a preview to test the SSO integration... 👀

[geropl]

@nandajavarma I had to push a fix for something I broke last week 😢

Otherwise, this works fine:

[geropl]

Tested and works fine! ✔️

[geropl]

/unblock

[geropl]

/unhold