Complete spec coverage for `Ci::Config::Entry::Bridge`

Ci::Config::Entry::Bridge has 92.31% spec coverage. The following lines should be covered:

# lines 36 and 38
34          validate on: :composed do
35              next unless bridge_needs.present?
36              next if bridge_needs.one? # THIS
37
38              errors.add(:config, 'should contain at most one bridge need') # THIS
39            end
40          end

and line 65:

          def self.visible?
65            true # THIS LINE IS NOT COVERED
          end