feat: ungate logs and metrics

[Litarnus]

Deprecates and changes enable_logs and enable_metrics to be effectively no-ops. The reason for this change is that those flags were basically just kill switches for the entire feature and disabled by default.
Users had to

1. add a log handler or call log functions directly and
2. enable the log feature to make sure they arrive.

Metrics are even more explicit since one has to invoke functions to emit metrics and we don't have any integrations.

Once this is merged, adding a handler or calling a log/metric function will be considered as a signal that this type of telemetry is wanted, and we will no longer respect the flag.

For anyone using those flags as kill switches: it's possible to implement kill switches using before_send_log and before_send_metric and return null in those callbacks.