Everywhere: Turn #if *_DEBUG into dbgln_if/if constexpr

Author: https://github.com/gunnarbeutner
Commit: 6cf59b6ae9
Pull-request: https://github.com/SerenityOS/serenity/pull/6796

Userland/Libraries/LibHTTP/Job.cpp

@@ -346,9 +346,7 @@ void Job::on_socket_connected()
         });
 
         if (!is_established()) {
-#if JOB_DEBUG
-            dbgln("Connection appears to have closed, finishing up");
-#endif
+            dbgln_if(JOB_DEBUG, "Connection appears to have closed, finishing up");
             finish_up();
         }
     });