Remove asl_log (Fixes #25380) (#25382)

Summary:
By default absolutely everything gets logged twice (facebook/react-native#25380).
This was introduced over 4 years ago here:

[React Native Log to ASL · facebook/react-native@d1b14ef · GitHub](facebook/react-native@d1b14ef)

with the reason to support ASL.
With this PR the support for that will be removed but I believe this is justified because:

- the benefit of not having every log message twice far outweighs the benefit of having Apple System Log.
- ASL was superseded by "unified logging" (yellow box on https://developer.apple.com/documentation/os/logging).
- I assume that people who use asl_log is very small. There is also very little information about it on the internet

## Changelog

[iOS] [Fixed] - Logs would get printed twice
Pull Request resolved: facebook/react-native#25382

Differential Revision: D16048052

Pulled By: cpojer

fbshipit-source-id: 51519570bbee79571e4ff63f433b9b70bcd55671

Author: JonnyBurger

React/Base/RCTLog.mm

@@ -9,7 +9,6 @@
 
 #import "RCTLog.h"
 
-#include <asl.h>
 #include <cxxabi.h>
 
 #import "RCTAssert.h"
@@ -58,26 +57,6 @@ void RCTSetLogThreshold(RCTLogLevel threshold) {
   NSString *log = RCTFormatLog([NSDate date], level, fileName, lineNumber, message);
   fprintf(stderr, "%s\n", log.UTF8String);
   fflush(stderr);
-
-  int aslLevel;
-  switch(level) {
-    case RCTLogLevelTrace:
-      aslLevel = ASL_LEVEL_DEBUG;
-      break;
-    case RCTLogLevelInfo:
-      aslLevel = ASL_LEVEL_NOTICE;
-      break;
-    case RCTLogLevelWarning:
-      aslLevel = ASL_LEVEL_WARNING;
-      break;
-    case RCTLogLevelError:
-      aslLevel = ASL_LEVEL_ERR;
-      break;
-    case RCTLogLevelFatal:
-      aslLevel = ASL_LEVEL_CRIT;
-      break;
-  }
-  asl_log(NULL, NULL, aslLevel, "%s", message.UTF8String);
 };
 
 void RCTSetLogFunction(RCTLogFunction logFunction)