[hooks_runner] [hooks] Shorten output dir paths

[dcharkes]

Closes: #2650

10 hex characters should be enough with up to 1000 configs.

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:code_assets	0.19.7	already published at pub.dev
package:data_assets	0.19.3	already published at pub.dev
package:ffi	2.1.5-wip	WIP (no publish necessary)
package:hooks	0.20.2	ready to publish	hooks-v0.20.2
package:hooks_runner	0.23.1	ready to publish	hooks_runner-v0.23.1
package:native_doc_dartifier	0.0.1-pre	already published at pub.dev
package:native_toolchain_c	0.17.2	already published at pub.dev
package:swift2objc	0.1.0	already published at pub.dev
package:swiftgen	0.1.1	already published at pub.dev

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

[github-actions]

PR Health

Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
hooks	None	0.20.1	0.20.2	0.20.1	✔️
hooks_runner	Breaking	0.23.0	0.23.1	0.24.0 Got "0.23.1" expected >= "0.24.0" (breaking changes)	⚠️

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// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

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pkgs/objective_c/lib/src/ns_input_stream.dart

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[coveralls]

coverage: 80.804%. remained the same
when pulling 057744c on shorter-paths
into 29cf243 on main.

[coveralls]

coverage: 80.804%. remained the same
when pulling faf7d0e on shorter-paths
into 29cf243 on main.

[goderbauer]

LGTM

[goderbauer]

typo: lenght

[goderbauer]

nit: drop the "note:", doesn't seem to add anything.

[goderbauer]

Same as below, document why this is preferred?

[goderbauer]

The second "sentence" seems to be incomplete. Maybe you meant "use" instead of "using"? It's also a little unclear why I should be doing that. Can you document the motivation for why it is preferred to create a subdirectory with the checksum over the relevant parts of the configuration? What do I get out of it?