Fine grained logging via FANCY_LOG always evaluates macro arguments #12885
Description
The ENVOY_LOG macro without fine grained logging doesn't evaluate variadic
arguments when the log level squelches the message. When going through
FANCY_LOG however, that no longer holds. Variadic arguments are always evaluated
regardless of the log level involved. This could be problematic from a perf point of view.
Context: #12830 (comment)