Add sane resource requests and limits defaults for Langfuse (and also the PostgreSQL subchart)

[frittentheke]

1. Currently the chart does not apply any resource requests or limits to the deployment of Langfuse and the resulting Pods by default. It would be nice if you could add this and provide sane defaults.

2. Additionally the used postgresql subchart, while already applying resource requests and limits, comes up with the resourcePreset of nano, see https://github.com/bitnami/charts/blob/main/bitnami/postgresql/README.md#resource-requests-and-limits and https://github.com/bitnami/charts/blob/main/bitnami/common/templates/_resources.tpl#L11-L15. It might make sense to provide saner defaults, also to encourage users do adjust to their own requirements.

[moraneden]

+1