This reverts commit a19b3436.

We added this logging to try and determine if the reason for Dart VM errors (https://github.com/flutter/flutter/issues/121231) was caused by some issue with the streams.
A recent test proves that is not the case:
https://ci.chromium.org/ui/p/flutter/builders/prod/Mac_ios%20platform_view_ios__start_up/11046/overview
The test shows the Dart VM url in the device log. However, the test log does NOT show a log for the Dart VM url but does show the stack trace, which all come from the main stream, which means it's not an issue with the secondary streams not receiving the log.

So reverting the debugging we added.