Update things under test/

[coord-e]

This PR updates to Ruby 4.0 under test/, and while I'm at it, update various things under test/. Updating sinatra and google-protobuf required a bit of extra work (see commit logs)

@cookpad/platform-task-force please review 🙏

[Copilot]

Pull request overview

This PR modernizes the test/ fixtures to run on Ruby 4.0 and updates the bundled dependencies (notably gRPC/protobuf and Sinatra/Rack) so the test containers continue to build and run with the newer runtime.

Changes:

• Bump Ruby to 4.0 for test containers and local test Ruby version (test/.ruby-version, Dockerfiles).
• Update gem dependency lockfiles under test/ (grpc/protobuf/rack/sinatra ecosystem, bundler 4 lock format with checksums).
• Regenerate gRPC health protobuf Ruby stubs and adjust Sinatra apps for newer Rack/Sinatra defaults (host authorization setting).

Reviewed changes

Copilot reviewed 10 out of 16 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/grpc/lib/health_services_pb.rb	Updated generated gRPC service stub; now references Watch RPC and new require path.
test/grpc/lib/health_pb.rb	Updated generated protobuf definitions to serialized descriptor format (protobuf v4 style).
test/grpc/Gemfile.lock	Bumped grpc/protobuf versions and updated lockfile format/checksums for bundler 4.
test/grpc/Dockerfile	Move gRPC test container to Ruby 4.0 base image.
test/Gemfile.lock	Update shared test gem lock (grpc/protobuf/rack) and bundler version/checksums.
test/eds/Gemfile.lock	Update EDS fixture dependencies to Sinatra 4 / Rack 3 ecosystem and bundler 4 lock format.
test/eds/Gemfile	Add rackup (and reorder) to support Sinatra/Rack 3 runtime.
test/eds/eds.rb	Configure Sinatra host authorization settings for the updated stack.
test/eds/Dockerfile	Move EDS test container to Ruby 4.0 base image.
test/docker-compose.yml	Remove deprecated version and remove unused expose stanza.
test/app/Gemfile.lock	Update app fixture dependencies to Sinatra 4 / Rack 3 ecosystem and bundler 4 lock format.
test/app/Gemfile	Add rackup dependency.
test/app/Dockerfile	Move app test container to Ruby 4.0 base image.
test/app/app.rb	Configure Sinatra host authorization settings for the updated stack.
test/.ruby-version	Bump test Ruby version to 4.0.

Files not reviewed (2)

• test/grpc/lib/health_pb.rb: Language not supported
• test/grpc/lib/health_services_pb.rb: Language not supported

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