Reverts: flutter/flutter#150733
Initiated by: gmackall
Reason for reverting: This breaks apps that use plugins that use `compileSdk` 31, some of which we use in our postsubmit (so it blocks the tree).
Original PR Author: gmackall
Reviewed By: {jason-simmons}
This change reverts the following previous change:
Manual engine roll to https://github.com/flutter/engine/pull/53532, because the roll requires lockfile generation.
This PR updates almost* all Gradle buildscripts in the Flutter repo the `example` and `dev` (in particular, in `dev/integration_tests` and in `dev/benchmarks`) directories to apply Flutter's Gradle plugins using the declarative `plugins {}` block.
*almost, because:
- add-to-app (aka hybrid) apps are not migrated (related https://github.com/flutter/flutter/issues/138756)
- apps that purposefully use build files to ensure backward compatibility (e.g. [`gradle_deprecated_settings`](https://github.com/flutter/flutter/tree/3.16.0/dev/integration_tests/gradle_deprecated_settings))
