Change type legacy_binary_affirmation_string to legacy_yes_or_no_string

[jouvin]

As stated in PR quattor/configuration-modules-core#816 ( https://github.com/quattor/configuration-modules-core/pull/816/files#r71087664), legacy_binary_affirmation_string does not make obvious what are the valid values of this type. Renaming this type to legacy_yes_or_no_string may be better and avoid having to look at the type definition to know the valid values.

Making the change involves modifying the configuration modules (core only?) using it. See quattor/configuration-modules-core#749.

[jrha]

It's a bit late to comment on this, the PR that introduced it was merged in April.
Instead of renaming it I feel like it would be better for us to make the effort to switch the components to use booleans.

[jrha]

See #111 and quattor/configuration-modules-core#749 for what would need to be changed.

[ned21]

Sorry I was on holiday in April so didn't see it to comment! :(