sysutils/fluent-bit: fix problems running the fluent-bit

There is a known problem with the default coro_stack_size being too
small. Double it to avoid failing to start. [1]

Since the daemon option seems to be somewhat funky [2], use daemon to
wrap the fluent-bit binary when running from the rc.d script.

[1] https://github.com/fluent/fluent-bit/issues/3716
PR: 255593 [2]