Release build+build_resolvers+build_runner 2.5.2, build_runner_core 9.1.0, build_test 3.1.0.

[davidmorgan]

And restore _test/test/sub-dir/subdir_test.dart which was somehow deleted in the previous commit.

[github-actions]

PR Health

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:build	2.5.2	ready to publish	build-v2.5.2
package:build_config	1.1.3-wip	WIP (no publish necessary)
package:build_daemon	4.0.5-wip	WIP (no publish necessary)
package:build_modules	5.0.13	already published at pub.dev
package:build_resolvers	2.5.2	ready to publish	build_resolvers-v2.5.2
package:build_runner	2.5.2	ready to publish	build_runner-v2.5.2
package:build_runner_core	9.1.0	ready to publish	build_runner_core-v9.1.0
package:build_test	3.1.0	ready to publish	build_test-v3.1.0
package:build_web_compilers	4.1.5	already published at pub.dev
package:scratch_space	1.0.3-wip	WIP (no publish necessary)

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.