GH-45069: [R][CI] Fix r-binary-packages crossbow job (#45070)
### Rationale for this change
GitHub phased out R from their Ubuntu images in their 24.04 image and this job started failing because of it. We now need to install R ourselves if a job needs it and uses ubuntu-latest (>=24.04).
### What changes are included in this PR?
Change in GHA workflow config to always install R.
### Are these changes tested?
They're testing here with crossbow.
### Are there any user-facing changes?
No.
* GitHub Issue: #45069
Authored-by: Bryce Mecum <petridish@gmail.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>
