ciao: use the same pipeline defaults everywhere

This MR refactors default CI settings to ensure consistent retry policies across all pipelines. It addresses the limitation that child pipelines cannot inherit defaults from the parent .gitlab-ci.yml by:

1. Removing the default section from the main .gitlab-ci.yml file
2. Adding the default section (with interruptible: true and retry policy) directly to 20+ child pipeline YAML files

This ensures all child pipelines explicitly have the same default retry behavior, which can help prevent pipeline failures that could be resolved with a retry. The change affects pipelines for base images, Debian, documentation, Grafazos, Homebrew, Etherlink, and other components.

This change is a bit more verbose, but also makes the default clearly stated at the beginning of each pipeline type.

Related to issue #8127 (closed) .

Next step : !19940 (merged)

Manually testing the MR

The semantic of the pipelines retry policy is not changed. Now the same policy is applied uniformly to every pipeline type.

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR