CI: use hyphen in child pipeline [pipeline_type]

What

Change child pipeline type from <parent>:<child> to <parent>-<child>. (Applicable only for child pipelines triggered by code verification pipelines.)

Why

To avoid needing to using quotes in datadog queries. E.g. in this datadog query, if you remove the quotes in @pipeline_type:"before_merging:debian_repository_partial" then you get an error message.

How

• One-character change in CIAO + regenerate yaml files.

Manually testing the MR

• make -C ci check
• check this other datadog query

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