Revert debugging prints added to `dart analyze`.

These prints were accidentally included in
https://dart-review.googlesource.com/c/sdk/+/345827, causing all runs
of `dart analyze` to output the communication with the analysis server
to standard output.

Change-Id: I6610ccc9d4b091d85809f8557daf6b96497d1c9a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/347067
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/dartdev/lib/src/analysis_server.dart

diff --git a/pkg/dartdev/lib/src/analysis_server.dart b/pkg/dartdev/lib/src/analysis_server.dart
index c0b6c71..1648f3f 100644
--- a/pkg/dartdev/lib/src/analysis_server.dart
+++ b/pkg/dartdev/lib/src/analysis_server.dart
@@ -248,14 +248,12 @@
     _requestCompleters[id] = completer;
     _process!.stdin.writeln(message);
 
-    print('==> $message');
     log.trace('==> $message');
 
     return completer.future;
   }
 
   void _handleServerResponse(String line) {
-    print('<== $line');
     log.trace('<== $line');
 
     final dynamic response = json.decode(line);