[kernel-service] Do not truncate errors generated by CFE

The errorString method was truncating the errors generated by CFE.

#56721

TEST=ci

Change-Id: I968f6dd481184a5e0f4a13bab85297e2fcc9b525
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/385360
Commit-Queue: Siva Annamalai <[email protected]>
Reviewed-by: Sigmund Cherem <[email protected]>

pkg/vm/bin/kernel_service.dart

@@ -1223,7 +1223,7 @@ class _CompilationError extends _CompilationFail {
   Status get status => Status.error;
 
   @override
-  String get errorString => errors.take(10).join('\n');
+  String get errorString => errors.join('\n');
 
   String toString() => "_CompilationError(${errorString})";