test(nrdot): fix stale branch reference in rabbitmq-al2023-amd64 recipe URL

The test def's recipe_content_url pointed at 'newrelic/open-install-
library/rabbitmq-recipe-changes/...' — a development branch that has
been deleted. curl returned 404 on every run, so the newrelic install
never actually loaded the recipe content, stopping silently after
'Connecting to the New Relic platform' phase. Ansible then registered
this as an SSH-drop after ~36s of nothing happening on the EC2.

Every run of this PR has reproduced the failure identically because
the URL is deterministically 404 — no transient. Point the URL at
main (where nrdot/rabbitmq/rhel.yml actually lives).

Change confined to this one file.

Author: pranav-new-relic

test/definitions/nrdot/rabbitmq/rabbitmq-al2023-amd64.json

@@ -36,7 +36,7 @@
         "source_repository": "https://github.com/newrelic/open-install-library.git",
         "deploy_script_path": "test/deploy/linux/newrelic-cli/install-recipe/roles",
         "params": {
-          "recipe_content_url": "https://raw.githubusercontent.com/newrelic/open-install-library/rabbitmq-recipe-changes/recipes/newrelic/infrastructure/nrdot/rabbitmq/rhel.yml",
+          "recipe_content_url": "https://raw.githubusercontent.com/newrelic/open-install-library/main/recipes/newrelic/infrastructure/nrdot/rabbitmq/rhel.yml",
           "recipe_targeted": "nrdot-rabbitmq",
           "validate_output": "NRDOT RabbitMQ\\s+\\(installed\\)",
           "env_var": "NEW_RELIC_CLI_SKIP_CORE=1 NR_CLI_RABBITMQ_ENDPOINT=http://localhost:15672 NR_CLI_RABBITMQ_USERNAME=admin NR_CLI_RABBITMQ_PASSWORD=admin NR_CLI_RABBITMQ_DEPLOYMENT_NAME=rabbitmq-al2023-amd64"