Reverts "Roll Flutter Engine from c50eb8a65097 to 015f3b1dec53 (2 revisions) (flutter#154691)" (flutter#154726)

Reverts: flutter#154691
Initiated by: jtmcdole
Reason for reverting: breaking flutter-dashboard
Original PR Author: engine-flutter-autoroll

Reviewed By: {fluttergithubbot}

This change reverts the following previous change:

flutter/engine@c50eb8a...015f3b1

2024-09-05 [email protected] [engine] always force platform channel responses to schedule a task. (flutter/engine#54975)
2024-09-05 [email protected] Fix unexpected ViewFocus events when Text Editing utilities change focus in the middle of a blur call. (flutter/engine#54965)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC [email protected],[email protected],[email protected] on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Author: auto-submit[bot]

bin/internal/engine.version

@@ -1 +1 @@
-015f3b1dec53979cfb5d026e84891720c4dd48e9
+c50eb8a65097efa38a8c8733efe238d40fb38d5e