configure_service: Only compile FormatEventStatusString when YUZU_ENABLE_BOXCAT is enabled

The function is unused if YUZU_ENABLE_BOXCAT is disabled, causing a
-Wunused-funciton error when compiled.

Wrapping it with `#ifdef YUZU_ENABLE_BOXCAT` to prevent compiling the
function when the variable is disabled. Opting to not use [[maybe
unused]] in case the function is totally unused in the future.