Fix cache gems CI step

The `cache gems` CI step attempts to package all gems in case they are
ever yanked. We need to include production, development, and test gems
to make this step useful.

Closes https://gitlab.com/gitlab-org/gitlab/-/issues/229520

.gitlab/ci/setup.gitlab-ci.yml

@@ -9,6 +9,7 @@ cache gems:
   stage: test
   needs: ["setup-test-env"]
   variables:
+    BUNDLE_INSTALL_FLAGS: --with=production --with=development --with=test --jobs=2 --path=vendor --retry=3 --quiet
     SETUP_DB: "false"
   script:
     - bundle package --all --all-platforms

scripts/prepare_build.sh

@@ -2,7 +2,7 @@
 
 export SETUP_DB=${SETUP_DB:-true}
 export USE_BUNDLE_INSTALL=${USE_BUNDLE_INSTALL:-true}
-export BUNDLE_INSTALL_FLAGS="--without=production --without=development --jobs=$(nproc) --path=vendor --retry=3 --quiet"
+export BUNDLE_INSTALL_FLAGS=${BUNDLE_INSTALL_FLAGS:-"--without=production --without=development --jobs=$(nproc) --path=vendor --retry=3 --quiet"}
 
 if [ "$USE_BUNDLE_INSTALL" != "false" ]; then
   bundle --version