We have installed RabbitMq 3.6.12 through Cloud Launcher on GKE and discovered that the RabbitMq version is using a version of Erlang that is not recommended by the RabbitMq community. The version of Erlang which you are using is 18.0 and is known to cause problems (one of them is limbo states). The recommended version on all distros is either 22.214.171.124 or 20.x.
On the version you have provided we have managed to kill Rabbit (Rabbit becomes unresponsive - something known as limbo state) when the system is overloaded. This does not happen when we upgraded Erlang to a recommended version. In order to follow the discussion on this issue please have a look at the thread we had with Michael Klishin from the Rabbit team over here
The last Erlang version update happened with version 3.6.10-0 as confirmed by your changelogs (Erlang version 18.0). This Erlang is incorrect and should be changed.
Can you please update your template to use a recommended Erlang version so that we avoid further heartaches to the community.