nimbus doesn't use/need glean-build

[mhammond]

Pull Request checklist

• Breaking changes: This PR follows our breaking change policy
  • [ ] This PR follows the breaking change policy:
    • This PR has no breaking API changes, or
    • There are corresponding PRs for our consumer applications that resolve the breaking changes and have been approved
• [ ] Quality: This PR builds and tests run cleanly
  • Note:
  • For changes that need extra cross-platform testing, consider adding [ci full] to the PR title.
  • If this pull request includes a breaking change, consider cutting a new release after merging.
• [ ] Tests: This PR includes thorough tests or an explanation of why it does not
• [ ] Changelog: This PR includes a changelog entry in CHANGELOG.md or an explanation of why it does not need one
  • Any breaking changes to Swift or Kotlin binding APIs are noted explicitly
• [ ] Dependencies: This PR follows our dependency management guidelines
  • Any new dependencies are accompanied by a summary of the due diligence applied in selecting them.

Branch builds: add [firefox-android: branch-name] to the PR title.