OBS allows to have packages with a too long description that cannot be branched anymore

[dcermak]

Issue Description

The package rubygem-mspec has a very long description (probably created via osc updatepacmetafromspec), but the package can now no longer be branched:

❯ osc branch devel:languages:ruby:extensions rubygem-mspec
BuildService API error: failed to branch: Title is too long (maximum is 250 characters)

Expected Result

• the package must not be allowed to have such a long description in the first place
• the branching should truncate the description if need be

How to Reproduce

1. osc branch devel:languages:ruby:extensions rubygem-mspec

[hennevogel]

There are 2 records on production that have longer titles than the Package.title length validation allows...

Package.where(id: Package.limit(5).order("CHAR_LENGTH(title) desc").pluck(:id)).map { |p| p.title.length } 
=> [255, 255, 249, 250, 250]