fix the nm-launcher not found error

[brianmcgillion]

hmmmm. how it ever worked???

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Description of changes

Fixes the nm-launcher path in the waybar so that it can be found.

Checklist for things done

• Summary of the proposed changes in the PR description
• More detailed description in the commit message(s)
• Commits are squashed into relevant entities - avoid a lot of minimal dev time commits in the PR
• Contribution guidelines followed
• Ghaf documentation updated with the commit - https://tiiuae.github.io/ghaf/
• PR linked to architecture documentation and requirement(s) (ticket id)
• Test procedure described (or includes tests). Select one or more:
  • Tested on Lenovo X1 x86_64
  • Tested on Jetson Orin NX or AGX aarch64
  • Tested on Polarfire riscv64
• Author has run make-checks and it passes
• All automatic Github Action checks pass - see actions
• Author has added reviewers and removed PR draft status
• Change requires full re-installation
• Change can be updated with nixos-rebuild ... switch

Instructions for Testing

• List all targets that this applies to:
  x1-carbon MVP user image

• Is this a new feature

  • List the test steps to verify:

• If it is an improvement how does it impact existing functionality?
  Bug fix that just appeared from nowhere.

[kajusnau]

This seems to be the correct way, works also in ewwbar