rgw: support conditional tracing using lua script

rgw: support conditional tracing using lua script

before lua script is being executed, we keep the tracer runtime configuration value, and then decides whether to trace or not the request based on the value that maybe changed during lua exeuction, so we can disable/enable tracing for request even if the tracer is in the opposite state at the same time

Signed-off-by: Omri Zeneva <ozeneva@redhat.com>