Reset logging name of Task at the end of setIntent

In case ProtoLog is enabled that evaluates "this.toString"
too early, which caches the intermediate states in the string.

Bug: 328114157
Test: Start dream activity from Screen saver Settings.
      "adb shell dumpsys activity activities" should show
      the task with "type=dream".
Change-Id: I21f8cf0f3d6d43e762bb45d8c5d6374eaae58378