Don't call [FIRApp configure] twice

Author: axel-op

packages/firebase_crashlytics/darwin/Classes/FirebaseCrashlyticsPlugin.m

@@ -18,8 +18,6 @@ + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar> *)registrar {
   FirebaseCrashlyticsPlugin *instance = [[FirebaseCrashlyticsPlugin alloc] init];
   [registrar addMethodCallDelegate:instance channel:channel];
 
-  [FIRApp configure];
-
   SEL sel = NSSelectorFromString(@"registerLibrary:withVersion:");
   if ([FIRApp respondsToSelector:sel]) {
     [FIRApp performSelector:sel withObject:LIBRARY_NAME withObject:LIBRARY_VERSION];