GH-44018: [R] Treat builds on R-universe as like `NOT_CRAN=true`
Rationale for this change
R-universe mimics CRAN's behavior quite well, but unlike CRAN, it does not reject external binary downloads. So allowing automatic download of libarrow binaries on R-universe may reduce CI run time on R-universe.
What changes are included in this PR?
Change to attempt to download libarrow binaries on R-universe.
Are these changes tested?
No.
Are there any user-facing changes?
No.
- GitHub Issue: #44018
:warning: GitHub issue #44018 has been automatically assigned in GitHub to PR creator.
After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit 9287bd7eca701b7cd3fd3e3b8bb30d82fcaea396.
There were no benchmark performance regressions. 🎉
The full Conbench report has more details. It also includes information about 1 possible false positive for unstable benchmarks that are known to sometimes produce them.