Use 'file://' scheme for local repository URL

Author: mark-vieira

.ci/jobs.t/elastic+elasticsearch+periodic+release-tests.yml

@@ -30,5 +30,5 @@
           curl --fail -o "${ML_IVY_REPO}/maven/org/elasticsearch/ml/ml-cpp/${ES_VERSION}/ml-cpp-${ES_VERSION}-deps.zip" https://artifacts-snapshot.elastic.co/ml-cpp/${ES_VERSION}-SNAPSHOT/downloads/ml-cpp/ml-cpp-${ES_VERSION}-SNAPSHOT-deps.zip
           curl --fail -o "${ML_IVY_REPO}/maven/org/elasticsearch/ml/ml-cpp/${ES_VERSION}/ml-cpp-${ES_VERSION}-nodeps.zip" https://artifacts-snapshot.elastic.co/ml-cpp/${ES_VERSION}-SNAPSHOT/downloads/ml-cpp/ml-cpp-${ES_VERSION}-SNAPSHOT-nodeps.zip
 
-          $WORKSPACE/.ci/scripts/run-gradle.sh -Dbwc.checkout.align=true -Dbuild.snapshot=false -Dbuild.ml_cpp.repo=${ML_IVY_REPO} \
+          $WORKSPACE/.ci/scripts/run-gradle.sh -Dbwc.checkout.align=true -Dbuild.snapshot=false -Dbuild.ml_cpp.repo=file://${ML_IVY_REPO} \
             -Dtests.jvm.argline=-Dbuild.snapshot=false -Dlicense.key=${WORKSPACE}/x-pack/license-tools/src/test/resources/public.key -Dbuild.id=deadbeef build