Set --enable_workspace on last_green CI build

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Author: mbland

.bazelci/presubmit.yml

@@ -36,6 +36,7 @@ tasks:
     shell_commands:
     # Install xmllint
     - sudo apt update && sudo apt install --reinstall libxml2-utils -y
+    - echo "build --enable_workspace" >> .bazelrc
     - "./test_rules_scala.sh || buildkite-agent annotate --style 'warning' \"Optional build with latest Bazel version failed, [see here](${BUILDKITE_BUILD_URL}#${BUILDKITE_JOB_ID}) (It is not mandatory but worth checking)\""
   test_rules_scala_macos:
     name: "./test_rules_scala"