Add log retention to lambda functions

[arturtamborski]

The logs are not that big, but they will be in a year or so when multiplied by 3-4 projects * 2 environments and we probably don't need the logs from dev anyway for longer than 2 weeks.

One policy document and cloudwatch_log_group with appropriate retention should be enough.
https://advancedweb.hu/how-to-manage-lambda-log-groups-with-terraform/