This reverts commit 275ab9c6.

Revert "Reland "Remove references to Observatory (#118577)""

This reverts commit 298d8c76.

This reverts commit 2df140f4.

Observatory is being deprecated for Dart 3.0 so it should no longer be
referenced in tooling messaging / flags.

See https://github.com/dart-lang/sdk/issues/50233

Speedup coverage test runs by using (new) coverage handle with caching.

On a `flutter test --coverage` run on `packages/flutter` the runtime goes from ~828 seconds to ~617 seconds, or a ~25% reduction in time spent (testing without coverage takes ~236 seconds so the overhead of `--coverage` in this case goes from ~592 seconds to ~381 seconds, or a ~35% reduction).

* Use libraryFilters flag to speed up coverage collection

* Allow libraryNames to be null

* Unconditionally enable the reportLines flag

* Fix analysis errors

* Use the report lines flag

* Handle major version bumps in the version check

* Fix existing tests and add a new test

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

Fixes #56194

Remove caching of FlutterView and poll forever if the list of flutter views is empty. Added test for missing release mode logic.

This reverts commit 209bdcb6.

Remove caching of FlutterView. Perhaps the FlutterView RPC might return an empty list if the VM is not quite up yet? We had some old logic to poll the flutter views RPC for up to 200ms. That doesn't seem like a great approach, so instead we could forgo it entirely and trust that either the views come up before the developer tries to interact, or we crash.

Finishes the gradual vm service migration by deleting the flutter tooling's vm_service

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs

This reverts commit 0dc5ea4a.

Move tools tests into a general.shard directory in preparation to changing how we shard tools tests (#36108)