Fly deployments on the free tier have ~256mb of memory available. Users
with large transaction histories were encountering out of memory errors
when attempting to export their data. This commit adds a node argument
to (more or less) run the garbage collector at a smaller memory usage,
helping keep users on flyio within their available limit.
Fly deployments with the previous template setting are running without
tini's subreaper capabilities. This change enables tini as a subreaper
in that environment.
