Limit test parallelism

Author: aledbf

.github/actions/integration-tests/action.yml

@@ -79,6 +79,7 @@ runs:
         TEST_BUILD_ID: ${{ inputs.test_build_id }}
         TEST_BUILD_URL: ${{ inputs.test_build_url }}
         TEST_BUILD_REF: ${{ inputs.test_build_ref }}
+        GOMAXPROCS: "4"
       run: |
         set -euo pipefail