GitLab

* [ci] fix git checkout for comment-triggered CI jobs

* set locale prior to installing packages

* comment out cuda

* change strategy for setting locale

* comment out R jobs

* comment out more CI jobs

* update locales before installing other packages

* remove unnecessary packages

* add libc6 back

* restore libicu and libssl

* Revert "comment out more CI jobs"

This reverts commit 8fd92144ad1dafc33ae699d7c3e159d8846e41b2.

* uncomment CI jobs

* revert more changes

* more reverting

* remove r_package.yml from diff

* [ci] upgrade actions/checkout to v2.4.0

* re-create GITHUB_WORKSPACE

* dont update cuda

* actually revert cuda

* use GitHub Actions to re-generate R configure

* Update R-package/README.md
Co-authored-by: James Lamb <jaylamb20@gmail.com>
Co-authored-by: James Lamb <jaylamb20@gmail.com>