map /tmp to something inside our docker containers

[stroomdev10]

One thing I have just noticed is that /tmp in our containers is not a volume and anything added in there will just be adding layers to the container. We prob ought to be mounting /tmp as tmpfs for all our containers, possibly with a size limit, so it is ram backed, volatile and won't increase the size of the container.

[at055612]

See
https://docs.docker.com/compose/compose-file/compose-file-v2/#tmpfs
https://docs.docker.com/storage/tmpfs/
Need to consider whether we impose a size limit to avoid it consuming all ram and what perms are needed.
Ideally applies to v6.1 upwards