chore: rework devcontainer setup

[lechnerc77]

Purpose

• Remove the automatic install of xdg-utils due to failures in the devcontainer setup
• Add comment on SSo setup in devcontainer file

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[X] Other... Please describe: rework dev container setup

How to Test

• Start the devcontainer

What to Check

Verify that the following are valid:

• The devcontainer starts without errors

Other Information

n/a

Checklist for reviewer

The following organizational tasks must be completed before merging this PR:

• [X] The PR is assigned to the Terraform project and a status is set (typically "in review").
• [X] The PR has the matching labels assigned to it.
• [X] The PR has a milestone assigned to it.
• [X] If the PR closes an issue, the issue is referenced.
• [X] Possible follow-up items are created and linked.