[release-0.18] Always use dedicated service account in device-plugin helm chart

[github-actions]

🤖 Automated backport of #1372 to release-0.18

⚠️ This PR has merge conflicts that need manual resolution.

Original PR: #1372
Original Author: @cdesiniotis

Cherry-picked commits (1):

• 81a0e5e Always use dedicated service account in device-plugin helm chart

Next Steps:

1. Review the conflicts in the "Files changed" tab
2. Check out this branch locally: git fetch origin backport-1372-to-release-0.18 && git checkout backport-1372-to-release-0.18
3. Resolve conflicts manually
4. Push the resolution: git push --force-with-lease origin backport-1372-to-release-0.18

---

Instructions for resolving conflicts

git fetch origin backport-1372-to-release-0.18
git checkout backport-1372-to-release-0.18
# Resolve conflicts in your editor
git add .
git commit
git push --force-with-lease origin backport-1372-to-release-0.18

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