Use :maximum instead of :within for length validators with a 0..N range

app/models/ci/variable.rb

app/models/concerns/issuable.rb

app/models/environment.rb

app/models/key.rb

app/models/namespace.rb

app/models/project.rb

app/models/snippet.rb

spec/lib/gitlab/github_import/importer_spec.rb

spec/models/ci/variable_spec.rb

spec/models/concerns/issuable_spec.rb

spec/models/environment_spec.rb

spec/models/key_spec.rb

spec/models/namespace_spec.rb

spec/models/project_spec.rb

spec/models/snippet_spec.rb

spec/models/user_spec.rb

spec/requests/api/deploy_keys_spec.rb

spec/support/matchers/is_within.rb